---
id: CVE-2025-9187
title: Memory safety bugs present in Firefox 141 and Thunderbird 141
summary: >-
  Memory safety bugs present in Firefox 141 and Thunderbird 141. Some of these
  bugs showed evidence of memory corruption and we presume that with enough
  effort some of these could have been exploited to run arbitrary code. This
  vulnerabili…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-119
vendor: mozilla
product: firefox
affected:
  - firefox < 142.0
  - thunderbird < 142.0
patched:
  - firefox 142.0
  - thunderbird 142.0
published: '2025-08-19'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T19:10:01.007'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-9187'
references:
  - url: >-
      https://bugzilla.mozilla.org/buglist.cgi?bug_id=1825621%2C1970079%2C1976736%2C1979072
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-64/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-70/'
    label: security@mozilla.org
tags:
  - nvd
epss: 0.00467
epssPercentile: 0.38045
ingestedAt: '2026-09-30T19:21:07.239Z'
---

## Overview

Memory safety bugs present in Firefox 141 and Thunderbird 141. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 142 and Thunderbird 142.

## Affected

- `firefox < 142.0`
- `thunderbird < 142.0`

## Remediation

Upgrade past the affected range:

- `firefox 142.0`
- `thunderbird 142.0`