CVE-2025-61925
📋 TL;DR
Astro web framework versions before 5.14.2 reflect unvalidated X-Forwarded-Host header values in Astro.url output, allowing attackers to manipulate URLs used for canonical links, login forms, or other purposes. This affects users running Astro in dynamic rendering mode behind caching proxies, where malicious values could be cached and served to subsequent users.
💻 Affected Systems
- Astro web framework
📦 What is this software?
Astro by Astro
⚠️ Risk & Real-World Impact
Worst Case
Attackers could redirect login credentials or sensitive form submissions to malicious servers, potentially leading to credential theft or session hijacking.
Likely Case
Canonical links and other URL references could be manipulated to point to malicious sites, potentially affecting SEO or enabling phishing attacks.
If Mitigated
With proper validation or patching, the header reflection is prevented, eliminating the injection vector.
🎯 Exploit Status
Requires ability to send HTTP requests with manipulated headers and a caching proxy in the infrastructure.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.14.2
Vendor Advisory: https://github.com/withastro/astro/security/advisories/GHSA-5ff5-9fcw-vg88
Restart Required: No
Instructions:
1. Update Astro package to version 5.14.2 or later using npm: npm update astro@^5.14.2 2. Verify the update with: npm list astro 3. Deploy the updated application.
🔧 Temporary Workarounds
Header validation middleware
allImplement custom middleware to validate or strip X-Forwarded-Host headers before they reach Astro.
Disable caching for dynamic content
allConfigure caching proxies to not cache pages that use Astro.url in dynamic rendering mode.
🧯 If You Can't Patch
- Implement reverse proxy or WAF rules to strip or validate X-Forwarded-Host headers
- Audit all uses of Astro.url in code and implement manual validation
🔍 How to Verify
Check if Vulnerable:
Check if Astro version is below 5.14.2 and application uses Astro.url in dynamic rendering mode behind a caching proxy.Check Version:
npm list astro | grep astroVerify Fix Applied:
Test that sending requests with malicious X-Forwarded-Host headers no longer affects Astro.url output values.📡 Detection & Monitoring
Log Indicators:
- Unusual X-Forwarded-Host header values in request logs
- Mismatches between Host and X-Forwarded-Host headers
Network Indicators:
- HTTP requests containing both Host and X-Forwarded-Host headers with different values
SIEM Query:
http.headers:X-Forwarded-Host AND NOT http.headers:Host=http.headers:X-Forwarded-Host