---
id: CVE-2025-6425
title: >-
  An attacker who enumerated resources from the WebCompat extension could have
  obtained a persistent UUID that identified the browser, and persisted between
  containers and normal/private browsing mode, but not profiles
summary: >-
  An attacker who enumerated resources from the WebCompat extension could have
  obtained a persistent UUID that identified the browser, and persisted between
  containers and normal/private browsing mode, but not profiles. This
  vulnerability …
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N'
cwe:
  - CWE-200
vendor: mozilla
product: firefox
affected:
  - firefox < 115.25.0
  - firefox < 140.0
  - 'firefox >= 116.0, < 128.12.0'
patched:
  - firefox 128.12.0
published: '2025-06-24'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T18:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-6425'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1717672'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-51/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-52/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-53/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-54/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-55/'
    label: security@mozilla.org
  - url: 'https://lists.debian.org/debian-lts-announce/2025/06/msg00029.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/07/msg00002.html'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.0031
epssPercentile: 0.21512
ingestedAt: '2026-09-30T18:17:24.442Z'
---

## Overview

An attacker who enumerated resources from the WebCompat extension could have obtained a persistent UUID that identified the browser, and persisted between containers and normal/private browsing mode, but not profiles. This vulnerability was fixed in Firefox 140, Firefox ESR 115.25, Firefox ESR 128.12, Thunderbird 140, and Thunderbird 128.12.

## Affected

- `firefox < 115.25.0`
- `firefox < 140.0`
- `firefox >= 116.0, < 128.12.0`

## Remediation

Upgrade past the affected range:

- `firefox 128.12.0`