CVE-2026-41321

The fetch() call for remote images in packages/integrations/cloudflare/src/utils/image-binding-transform.ts (line 28) uses the default redirect: 'follow' behavior. This allows the Cloudflare Worker to follow HTTP redirects to arbitrary URLs, bypassing the isRemoteAllowed() domain allowlist check which only validates the initial URL.

All three other image fetch paths in the codebase correctly use { redirect: 'manual' }. This is an incomplete fix for GHSA-qpr4-c339-7vq8.

Confirmed on HEAD.

Root Cause

image-binding-transform.ts line 28:

const content = await (isRemotePath(href) ? fetch(imageSrc) : assets.fetch(imageSrc));

Missing { redirect: 'manual' }. The three protected paths:

// image-passthrough-endpoint.ts:23
response = await fetch(href, { redirect: 'manual' });

// assets/endpoint/shared.ts:11
const res = await fetch(src, { redirect: 'manual' });

// assets/utils/remoteProbe.ts:53
const response = await fetch(url, { redirect: 'manual' });

PoC

Demonstrated with Node.js that fetch() without redirect: 'manual' follows 302 redirects to arbitrary destinations:

# Server A (allowed domain) returns 302 → Server B (internal)
fetch('http://allowed:19741/img.jpg')                        → follows 302 → hits http://internal:19742/secret
fetch('http://allowed:19741/img.jpg', {redirect:'manual'})   → returns 302, internal server NOT hit

Attack path: attacker finds an open redirect on an allowed domain, crafts /_image?href=https://allowed-cdn.com/redirect?url=http://internal-service/, and the Worker follows the redirect to the unauthorized destination.

Bypasses the image.domains and image.remotePatterns allowlist for the default Cloudflare image service (cloudflare-binding). Enables blind SSRF to domains not in the allowlist. Same vulnerability class as GHSA-qpr4-c339-7vq8 (HIGH) which fixed the passthrough endpoint but missed this one.

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

CVE-2026-41321 has a CVSS score of 2.2 (Low). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (13.1.10); upgrading removes the vulnerable code path.

Kodem intelligence

const content = await (isRemotePath(href) ? fetch(imageSrc, { redirect: 'manual' }) : assets.fetch(imageSrc));

1. What is CVE-2026-41321? CVE-2026-41321 is a low-severity server-side request forgery (SSRF) vulnerability in @astrojs/cloudflare (npm), affecting versions < 13.1.10. It is fixed in 13.1.10. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is CVE-2026-41321? CVE-2026-41321 has a CVSS score of 2.2 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @astrojs/cloudflare are affected by CVE-2026-41321? @astrojs/cloudflare (npm) versions < 13.1.10 is affected.
4. Is there a fix for CVE-2026-41321? Yes. CVE-2026-41321 is fixed in 13.1.10. Upgrade to this version or later.
5. Is CVE-2026-41321 exploitable, and should I be worried? Whether CVE-2026-41321 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-41321 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-41321? Upgrade @astrojs/cloudflare to 13.1.10 or later.