CVE-2025-14324
📋 TL;DR
A critical JIT miscompilation vulnerability in Firefox's JavaScript engine allows arbitrary code execution when processing malicious JavaScript. This affects Firefox, Firefox ESR, and Thunderbird users running outdated versions. Attackers can exploit this to take full control of affected browsers.
💻 Affected Systems
- Firefox
- Firefox ESR
- Thunderbird
📦 What is this software?
Firefox by Mozilla
Firefox by Mozilla
Firefox by Mozilla
Thunderbird by Mozilla
Thunderbird by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, and lateral movement within networks.
Likely Case
Browser compromise allowing session hijacking, credential theft, and malware installation.
If Mitigated
Limited impact if browser sandboxing works properly, but still potential for data exfiltration.
🎯 Exploit Status
CVSS 9.8 indicates trivial exploitation. While no public PoC exists, similar JIT vulnerabilities are frequently weaponized.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox 146+, Firefox ESR 115.31+, Firefox ESR 140.6+, Thunderbird 146+, Thunderbird 140.6+
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2025-92/
Restart Required: Yes
Instructions:
1. Open browser settings 2. Navigate to 'About Firefox/Thunderbird' 3. Allow automatic update or manually download from mozilla.org 4. Restart browser
🔧 Temporary Workarounds
Disable JavaScript
allTemporarily disable JavaScript execution to prevent exploitation
about:config -> javascript.enabled = false
Enable Enhanced Tracking Protection
allBlocks known malicious scripts
Settings -> Privacy & Security -> Enhanced Tracking Protection -> Strict
🧯 If You Can't Patch
- Network segmentation to isolate vulnerable browsers from critical systems
- Implement application allowlisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check browser version in settings: Firefox/Thunderbird -> Help -> AboutCheck Version:
firefox --version or thunderbird --versionVerify Fix Applied:
Confirm version is at or above patched versions listed in fix_official📡 Detection & Monitoring
Log Indicators:
- Browser crash reports with JIT-related errors
- Unusual JavaScript execution patterns
Network Indicators:
- Traffic to known exploit domains
- Unusual outbound connections from browsers
SIEM Query:
source="browser_logs" AND (event="crash" AND component="JIT") OR (javascript_execution_anomaly)🔗 References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1996840
- https://www.mozilla.org/security/advisories/mfsa2025-92/
- https://www.mozilla.org/security/advisories/mfsa2025-93/
- https://www.mozilla.org/security/advisories/mfsa2025-94/
- https://www.mozilla.org/security/advisories/mfsa2025-95/
- https://www.mozilla.org/security/advisories/mfsa2025-96/
