CVE-2026-2784
📋 TL;DR
This CVE describes a DOM security component mitigation bypass vulnerability in Firefox. Attackers could potentially bypass security controls to execute malicious code or access restricted content. Affected users include anyone running Firefox versions below 148 or Firefox ESR versions below 140.8.
💻 Affected Systems
- Mozilla Firefox
- Mozilla Firefox ESR
📦 What is this software?
Firefox by Mozilla
Firefox by Mozilla
Thunderbird by Mozilla
Thunderbird by Mozilla
⚠️ Risk & Real-World Impact
Worst Case
Complete browser compromise allowing arbitrary code execution, data theft, and system access
Likely Case
Limited privilege escalation within browser context, potential session hijacking or data exfiltration
If Mitigated
Minimal impact with proper browser sandboxing and security controls in place
🎯 Exploit Status
Exploitation requires user to visit malicious website or interact with crafted content
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firefox 148, Firefox ESR 140.8
Vendor Advisory: https://www.mozilla.org/security/advisories/mfsa2026-13/
Restart Required: Yes
Instructions:
1. Open Firefox menu > Help > About Firefox. 2. Allow browser to check for updates. 3. Restart Firefox when prompted. 4. Verify version is 148 or higher (or ESR 140.8+).
🔧 Temporary Workarounds
Disable JavaScript
allTemporarily disable JavaScript to prevent exploitation vectors
about:config > javascript.enabled = false
Use Content Security Policy
allImplement strict CSP headers to limit script execution
Content-Security-Policy: script-src 'self'
🧯 If You Can't Patch
- Restrict browser to trusted websites only using enterprise policies
- Implement network-level filtering to block malicious content delivery
🔍 How to Verify
Check if Vulnerable:
Check Firefox version in Help > About Firefox menuCheck Version:
firefox --versionVerify Fix Applied:
Confirm version is Firefox 148+ or Firefox ESR 140.8+📡 Detection & Monitoring
Log Indicators:
- Unusual DOM manipulation patterns
- Security policy violation logs
- Sandbox escape attempts
Network Indicators:
- Requests to known exploit domains
- Unusual script loading patterns
SIEM Query:
source="firefox.log" AND (event="security_violation" OR event="sandbox_escape")