CVE-2025-66648
📋 TL;DR
CVE-2025-66648 is a cross-site scripting (XSS) vulnerability in vega-functions library that allows attackers to execute arbitrary JavaScript code by exploiting an internal function not part of the public API. This affects any application using vulnerable versions of vega-functions that processes untrusted user input. The vulnerability is particularly dangerous for web applications that allow user-supplied Vega expressions.
💻 Affected Systems
- vega-functions
📦 What is this software?
Vega Functions by Vega Functions Project
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover, session hijacking, data theft, or malware distribution through client-side code execution in users' browsers.
Likely Case
Stealing user sessions, performing actions on behalf of authenticated users, or defacing web applications.
If Mitigated
Limited impact if proper input validation and output encoding are implemented, though the vulnerability bypasses some standard XSS protections.
🎯 Exploit Status
Exploitation requires the attacker to supply malicious input to a vulnerable Vega expression parser. No authentication is needed if the vulnerable endpoint is publicly accessible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.1.1
Vendor Advisory: https://github.com/vega/vega/security/advisories/GHSA-m9rg-mr6g-75gm
Restart Required: No
Instructions:
1. Update vega-functions dependency to version 6.1.1 or later. 2. For npm: run 'npm update vega-functions'. 3. For yarn: run 'yarn upgrade vega-functions'. 4. Rebuild and redeploy your application.
🔧 Temporary Workarounds
No workaround available
allThe vendor advisory states there is no workaround besides upgrading. Input validation and CSP do not prevent this specific vulnerability.
🧯 If You Can't Patch
- Disable user-supplied Vega expression functionality entirely
- Implement strict input validation and sanitization for all user inputs that could reach Vega expression parser
🔍 How to Verify
Check if Vulnerable:
Check package.json or package-lock.json for vega-functions version. If version is below 6.1.1, the system is vulnerable.Check Version:
npm list vega-functions | grep vega-functionsVerify Fix Applied:
Verify vega-functions version is 6.1.1 or higher in package.json and that the updated version is actually being used in production.📡 Detection & Monitoring
Log Indicators:
- Unusual Vega expression patterns in user inputs
- JavaScript code patterns in Vega expression logs
- Multiple failed expression parsing attempts
Network Indicators:
- POST/PUT requests containing suspicious JavaScript patterns in Vega expression parameters
- Unusual content-type headers for Vega expression endpoints
SIEM Query:
source="web_logs" AND (vega OR expression) AND (javascript OR script OR eval OR alert)