Privilege Escalation in Firefox WebExtensions by Mozilla
CVE-2026-109778

Currently unrated

Key Information:

Vendor: Mozilla
Status: Firefox
Vendor: CVE Published:; 13 October 2026

What is CVE-2026-109778?

A privilege escalation vulnerability exists within the WebExtensions component of Firefox, allowing unauthorized access to elevated privileges. This issue impacts users who rely on WebExtensions for enhanced browser functionality. Mozilla has addressed this vulnerability in the updates: Firefox version 158 and Firefox ESR version 153.5, ensuring users benefit from enhanced security measures.

Affected Version(s)

Firefox 153.5

Firefox 158

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2070547

https://www.mozilla.org/security/advisories/mfsa2026-106/

https://www.mozilla.org/security/advisories/mfsa2026-108/

Download the Critical Vulnerability Management Cheat Sheet

Timeline

Vulnerability published
Oct 13, 2026
Vulnerability Reserved
Oct 13, 2026

Credit

Mozilla

CVE-2026-109778 Data

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