---
id: CVE-2026-74983
title: Mitigation bypass in the Data Loss Prevention component
summary: >-
  Mitigation bypass in the Data Loss Prevention component. This vulnerability
  was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird
  154, Thunderbird 140.14, and Thunderbird 153.1.
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N'
cvssSource: adp
vendor: Mozilla
product: Firefox
affected:
  - Firefox
  - Thunderbird
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-08-19T13:35:00.550070Z'
published: '2026-08-18'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T18:44:09.670Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74983'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2051897'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-74/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-76/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-77/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-78/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-79/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-80/'
tags:
  - cve.org
epss: 0.00434
epssPercentile: 0.35003
ingestedAt: '2026-09-17T19:26:25.345Z'
---

## Overview

Mitigation bypass in the Data Loss Prevention component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

## Affected

- `Firefox`
- `Thunderbird`

## Remediation

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