CVE-2025-64525
📋 TL;DR
Astro web framework versions 2.16.0 to 5.15.4 with on-demand rendering are vulnerable to header injection attacks. Attackers can manipulate x-forwarded-proto and x-forwarded-port headers to bypass middleware protections, poison caches, conduct SSRF attacks, and evade WAFs. This affects any Astro deployment using on-demand rendering behind proxies or CDNs.
💻 Affected Systems
- Astro web framework
📦 What is this software?
Astro by Astro
⚠️ Risk & Real-World Impact
Worst Case
Complete middleware bypass allowing unauthorized access to protected routes, cache poisoning leading to widespread DoS, SSRF attacks against internal systems, and WAF evasion enabling other attacks.
Likely Case
Cache poisoning and URL pollution attacks when deployed behind CDNs, potentially leading to denial of service and content manipulation.
If Mitigated
Limited impact if proper header validation is implemented at proxy/CDN layer or if on-demand rendering is disabled.
🎯 Exploit Status
Exploitation requires ability to send HTTP requests with custom headers, which is trivial for attackers. No public exploit code has been released but the vulnerability is straightforward to weaponize.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.15.5
Vendor Advisory: https://github.com/withastro/astro/security/advisories/GHSA-hr2q-hp5q-x767
Restart Required: Yes
Instructions:
1. Update Astro package to version 5.15.5 or later using npm update astro@latest or yarn upgrade astro@latest. 2. Restart your Astro development server or production deployment. 3. Verify the update with npm list astro or yarn list astro.
🔧 Temporary Workarounds
Disable on-demand rendering
allSwitch to static site generation (SSG) mode which is not affected by this vulnerability
Set output: 'static' in astro.config.mjs
Proxy header validation
allConfigure reverse proxies or CDNs to strip or validate x-forwarded-proto and x-forwarded-port headers
🧯 If You Can't Patch
- Implement strict header validation at reverse proxy/CDN layer to strip or sanitize x-forwarded-proto and x-forwarded-port headers
- Disable on-demand rendering and switch to static site generation mode if possible
🔍 How to Verify
Check if Vulnerable:
Check package.json for Astro version between 2.16.0 and 5.15.4 and verify on-demand rendering is enabledCheck Version:
npm list astro | grep astro or yarn list astro | grep astroVerify Fix Applied:
Verify Astro version is 5.15.5 or higher using npm list astro or yarn list astro📡 Detection & Monitoring
Log Indicators:
- Unusual x-forwarded-proto or x-forwarded-port header values in request logs
- Requests to unexpected URLs or protocols
Network Indicators:
- HTTP requests with manipulated x-forwarded headers
- Unexpected protocol switching in request chains
SIEM Query:
http.headers:x-forwarded-proto NOT IN ['http', 'https'] OR http.headers:x-forwarded-port NOT MATCHES '^[0-9]+$'🔗 References
- https://github.com/withastro/astro/blob/970ac0f51172e1e6bff4440516a851e725ac3097/packages/astro/src/core/app/node.ts#L121
- https://github.com/withastro/astro/blob/970ac0f51172e1e6bff4440516a851e725ac3097/packages/astro/src/core/app/node.ts#L97
- https://github.com/withastro/astro/commit/dafbb1ba29912099c4faff1440033edc768af8b4
- https://github.com/withastro/astro/security/advisories/GHSA-hr2q-hp5q-x767
