CVE-2026-2780
📋 TL;DR
This CVE describes a privilege escalation vulnerability in Firefox's Netmonitor component. Attackers could exploit this to gain elevated privileges within the browser. It affects Firefox versions below 148 and 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
An attacker could execute arbitrary code with elevated privileges, potentially compromising the entire system if combined with other vulnerabilities.
Likely Case
Attackers could bypass browser security restrictions, access sensitive data, or perform unauthorized actions within the browser context.
If Mitigated
With proper browser sandboxing and security controls, impact would be limited to the browser process.
🎯 Exploit Status
Exploitation likely requires user interaction or other initial access vectors.
🛠️ 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. 2. Click menu → Help → About Firefox. 3. Allow automatic update to complete. 4. Restart Firefox when prompted.
🔧 Temporary Workarounds
Disable Netmonitor
allDisable the Netmonitor component to remove attack surface
about:config → Set 'devtools.netmonitor.enabled' to false
🧯 If You Can't Patch
- Restrict browser usage to trusted websites only
- Implement application whitelisting to prevent unauthorized browser execution
🔍 How to Verify
Check if Vulnerable:
Check Firefox version in Help → About FirefoxCheck Version:
firefox --versionVerify Fix Applied:
Confirm version is Firefox ≥148 or Firefox ESR ≥140.8📡 Detection & Monitoring
Log Indicators:
- Unusual Netmonitor component activity
- Privilege escalation attempts in browser logs
Network Indicators:
- Suspicious browser extension communications
- Unexpected browser process network connections
SIEM Query:
source="firefox" AND (event="privilege_escalation" OR component="netmonitor")