CVE-2026-109739

CVSS 8.8 (high) · published 2026-10-13

Privilege escalation in the WebExtensions component. This vulnerability was fixed in Firefox 158 and Thunderbird 158.

Weakness: CWE-269

Source: NVD CVE-2026-109739

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2049069
• https://www.mozilla.org/security/advisories/mfsa2026-106/
• https://www.mozilla.org/security/advisories/mfsa2026-109/

Check your software

Connect an AI agent to the FixLane MCP server or ask the Telegram bot to check what you have installed against incidents with a verified fixed version.