CVE-2026-2802
📋 TL;DR
A race condition vulnerability in Firefox's JavaScript garbage collector (GC) component could allow attackers to execute arbitrary code or cause denial of service. This affects Firefox versions before 148, potentially impacting all users who haven't updated their browsers.
💻 Affected Systems
- Mozilla Firefox
📦 What is this software?
Firefox by Mozilla
Thunderbird by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or malware installation.
Likely Case
Browser crash or denial of service, potentially enabling sandbox escape in combination with other vulnerabilities.
If Mitigated
Limited impact due to Firefox's sandboxing and exploit mitigations, possibly resulting only in tab crashes.
🎯 Exploit Status
Race conditions are difficult to exploit reliably but can be weaponized by skilled attackers. Requires JavaScript execution in browser context.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox 148
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2026-13/
Restart Required: Yes
Instructions:
1. Open Firefox menu > Help > About Firefox. 2. Allow automatic update to version 148. 3. Restart Firefox when prompted. 4. Verify version in About Firefox shows 148 or higher.
🔧 Temporary Workarounds
Disable JavaScript
allTemporarily disable JavaScript execution to prevent exploitation
about:config > javascript.enabled = false
Use Content Security Policy
allImplement strict CSP to limit script execution
Content-Security-Policy: script-src 'self'
🧯 If You Can't Patch
- Restrict Firefox usage to trusted websites only
- Implement network segmentation to isolate Firefox instances
🔍 How to Verify
Check if Vulnerable:
Check Firefox version in menu > Help > About Firefox. If version is less than 148, system is vulnerable.Check Version:
firefox --versionVerify Fix Applied:
Confirm Firefox version is 148 or higher in About Firefox dialog.📡 Detection & Monitoring
Log Indicators:
- Multiple rapid JavaScript heap allocation failures
- Unexpected browser process crashes
- Sandbox violation attempts
Network Indicators:
- Suspicious JavaScript payloads targeting GC timing
- Multiple rapid requests to trigger race conditions
SIEM Query:
source="firefox.log" AND ("crash" OR "heap" OR "GC") AND frequency > 10 within 1s