---
id: CVE-2026-109746
title: 'Mitigation bypass in the DOM: Security component'
summary: >-
  Mitigation bypass in the DOM: Security component. This vulnerability was fixed
  in Firefox 158 and Thunderbird 158.
severity: high
published: '2026-10-13'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T19:18:38.723'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109746'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2063005'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-106/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-109/'
    label: security@mozilla.org
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-13T13:27:04.005Z'
vendor: Mozilla
product: Firefox
affected:
  - Firefox
  - Thunderbird
epss: 0.003
epssPercentile: 0.22516
cvss: 7.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L'
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-19T12:21:04.583316Z'
cvssSource: adp
---

## Overview

Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 158 and Thunderbird 158.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.