CVE-2026-84121EPSS p22.7%

CVE-2026-84121CVE-2026-84121

mozilla / firefox

Description

Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

Scoring

CVSS 9.6 ()
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
EPSS0.32% probability of exploitation · percentile 22.7% · 2026-10-05T12:00:23Z
Last modified2026-09-02
Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.