CVE-2025-64765
📋 TL;DR
This vulnerability allows attackers to bypass middleware validation checks in Astro web applications by using URL-encoded path variants. The mismatch between how Astro normalizes paths for routing versus middleware validation enables access to protected routes that should be blocked. All Astro applications using middleware for route protection prior to version 5.15.8 are affected.
💻 Affected Systems
- Astro web framework
📦 What is this software?
Astro by Astro
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain unauthorized access to protected administrative interfaces, sensitive data endpoints, or privileged functionality that should be restricted by middleware validation.
Likely Case
Bypass of authentication or authorization middleware allowing access to restricted content or functionality that should require proper credentials.
If Mitigated
Limited impact if additional security layers exist beyond middleware validation, or if protected routes contain no sensitive functionality.
🎯 Exploit Status
Exploitation requires crafting URL-encoded paths to bypass middleware validation while still matching route patterns. No special tools or deep technical knowledge required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.15.8
Vendor Advisory: https://github.com/withastro/astro/security/advisories/GHSA-ggxq-hp9w-j794
Restart Required: Yes
Instructions:
1. Update Astro package to version 5.15.8 or later
2. Run 'npm update astro' or 'yarn upgrade astro'
3. Restart your Astro development server
4. Rebuild and redeploy your application
🔧 Temporary Workarounds
Middleware path normalization
allManually apply decodeURI() to context.url.pathname in all middleware functions to ensure consistent path normalization.
// In middleware: const normalizedPath = decodeURI(context.url.pathname);
🧯 If You Can't Patch
- Implement additional authentication/authorization checks at the route handler level beyond middleware validation.
- Use web application firewall (WAF) rules to block requests with URL-encoded paths to protected routes.
🔍 How to Verify
Check if Vulnerable:
Check package.json for Astro version below 5.15.8 and verify if middleware is used for route protection.Check Version:
npm list astro | grep astro OR check package.json for "astro" versionVerify Fix Applied:
Test protected routes with URL-encoded path variants to ensure middleware validation blocks access as expected.📡 Detection & Monitoring
Log Indicators:
- HTTP requests to protected routes with URL-encoded characters in paths
- Successful access to middleware-protected routes without proper authentication logs
Network Indicators:
- HTTP requests containing %2F, %2E, or other URL-encoded path segments to protected endpoints
SIEM Query:
http.url:*%* AND http.status:200 AND http.path:/protected/*