CVE-2026-84121

Published Sep 1, 2026

Last updated 14 hours ago

Overview

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.
Source
security@mozilla.org
NVD status
Analyzed
Products
firefox, thunderbird

Risk scores

CVSS 3.1

Type
Secondary
Base score
9.6
Impact score
6
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Severity
CRITICAL

Weaknesses

134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-416

Social media

Hype score
Not currently trending

Configurations