CVE-2026-109739

high

Description

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

References

https://www.mozilla.org/security/advisories/mfsa2026-109/

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

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-98501

https://bugzilla.mozilla.org/show_bug.cgi?id=2049069

Details

Source: Mitre, NVD

Published: 2026-10-13

Updated: 2026-10-14

Risk Information

CVSS v2

Base Score: 9

Vector: CVSS2#AV:N/AC:L/Au:S/C:C/I:C/A:C

Severity: High

CVSS v3

Base Score: 8.8

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Severity: High

EPSS

EPSS: 0.00157