CVE-2026-109739

Privilege escalation in the WebExtensions component

State: Published
Severity: 8.8 High
Published: Oct 13, 2026
Updated: Oct 14, 2026
Reserved: Oct 13, 2026

Description

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

Scores

CVSS	Score	Vector	Source
3.1	8.8 High	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	CISA-ADP

Weaknesses

CWE-269 Improper Privilege Management

Affected Products

Product	Versions
FirefoxMozilla	158 and laterNot affected
ThunderbirdMozilla	158 and laterNot affected

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/

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