CVE-2026-109739 Privilege escalation in the WebExtensions component

Description

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

Affected products and versions

Product	Affected versions	Fixed in
Firefox 158	earliest → < 158	158
Thunderbird 158	earliest → < 158	158

Other CVEs of Firefox

The 2221 CVEs of Firefox →

CVE-2026-120572 Incorrect boundary conditions in the Layout: Block and Inline component 8.8 High CVE-2026-118027 Frame poisoning in the Layout component 9.1 Critical CVE-2026-118025 Other issue in the SVG component 8.8 High CVE-2026-118026 Invalid pointer in the JavaScript: GC component 8.8 High