CVE-2025-64764
📋 TL;DR
A reflected cross-site scripting (XSS) vulnerability exists in Astro web framework when using server islands feature. Attackers can inject malicious scripts that execute in users' browsers when they visit crafted URLs. This affects all Astro applications using server islands prior to version 5.15.8.
💻 Affected Systems
- Astro web framework
📦 What is this software?
Astro by Astro
⚠️ Risk & Real-World Impact
Worst Case
Attackers steal user session cookies, credentials, or perform actions on behalf of authenticated users, potentially leading to account takeover and data theft.
Likely Case
Attackers execute arbitrary JavaScript in victim browsers, potentially stealing session tokens or redirecting users to malicious sites.
If Mitigated
With proper input validation and output encoding, the impact is limited, but the vulnerability still exists in the framework itself.
🎯 Exploit Status
Reflected XSS typically requires user interaction (clicking malicious link) but is straightforward to exploit once the vulnerability is understood.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.15.8
Vendor Advisory: https://github.com/withastro/astro/security/advisories/GHSA-wrwg-2hg8-v723
Restart Required: Yes
Instructions:
1. Update Astro package: npm update astro@5.15.8
2. Restart your Astro development server
3. Rebuild and redeploy your application
🔧 Temporary Workarounds
Disable server islands
allTemporarily disable server islands feature if not essential
Remove or comment out server island components in your Astro project
🧯 If You Can't Patch
- Implement strict Content Security Policy (CSP) headers to restrict script execution
- Deploy web application firewall (WAF) with XSS protection rules
🔍 How to Verify
Check if Vulnerable:
Check package.json for Astro version below 5.15.8 and verify server islands are usedCheck Version:
npm list astro | grep astroVerify Fix Applied:
Confirm Astro version is 5.15.8 or higher in package.json and dependencies📡 Detection & Monitoring
Log Indicators:
- Unusual URL parameters containing script tags or JavaScript code
- Multiple failed requests with suspicious query strings
Network Indicators:
- HTTP requests with script payloads in query parameters
- Unusual redirect patterns
SIEM Query:
web.logs | where url contains "<script>" or url contains "javascript:"