CVE-2025-55207

Following https://github.com/withastro/astro/security/advisories/GHSA-cq8c-xv66-36gw, there's still an Open Redirect vulnerability in a subset of Astro deployment scenarios.

Details

Astro 5.12.8 fixed a case where https://example.com//astro.build/press would redirect to the external origin //astro.build/press. However, with the Node deployment adapter in standalone mode and trailingSlash set to "always" in the Astro configuration, https://example.com//astro.build/press still redirects to //astro.build/press.

Proof of Concept

1. Create a new minimal Astro project ([email protected])
2. Configure it to use the Node adapter (@astrojs/[email protected]) and force trailing slashes:

   // astro.config.mjs
   import { defineConfig } from 'astro/config';
   import node from '@astrojs/node';
   
   export default defineConfig({
     trailingSlash: 'always',
     adapter: node({ mode: 'standalone' }),
   });
   

3. Build the site by running astro build.
4. Run the server, e.g. with astro preview.
5. Append //astro.build/press to the preview URL, e.g. http://localhost:4321//astro.build/press
6. The site will redirect to the external Astro Build origin.

Example reproduction

1. Open this StackBlitz reproduction.
2. Open the preview in a separate window so the StackBlitz embed doesn't cause security errors.
3. Append //astro.build/press to the preview URL, e.g. https://x.local-corp.webcontainer.io//astro.build/press.
4. See it redirect to the external Astro Build origin.

This is classified as an Open Redirection vulnerability (CWE-601). It affects any user who clicks on a specially crafted link pointing to the affected domain. Since the domain appears legitimate, victims may be tricked into trusting the redirected page, leading to possible credential theft, malware distribution, or other phishing-related attacks.

No authentication is required to exploit this vulnerability. Any unauthenticated user can trigger the redirect by clicking a malicious link.

Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites. Typical impact: phishing and credential harvesting via a trusted domain.

Kodem intelligence

1. What is CVE-2025-55207? CVE-2025-55207 is a medium-severity open redirect vulnerability in @astrojs/node (npm), affecting versions <= 9.4.0. It is fixed in 9.4.1. Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites.
2. Which versions of @astrojs/node are affected by CVE-2025-55207? @astrojs/node (npm) versions <= 9.4.0 is affected.
3. Is there a fix for CVE-2025-55207? Yes. CVE-2025-55207 is fixed in 9.4.1. Upgrade to this version or later.
4. Is CVE-2025-55207 exploitable, and should I be worried? Whether CVE-2025-55207 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
5. What actually determines whether CVE-2025-55207 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.
6. How do I fix CVE-2025-55207? Upgrade @astrojs/node to 9.4.1 or later.