---
id: CVE-2025-4092
title: Memory safety bugs present in Firefox 137 and Thunderbird 137
summary: >-
  Memory safety bugs present in Firefox 137 and Thunderbird 137. 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: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-119
vendor: mozilla
product: firefox
affected:
  - firefox < 138.0
  - thunderbird < 138.0
patched:
  - firefox 138.0
  - thunderbird 138.0
published: '2025-04-29'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T18:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-4092'
references:
  - url: >-
      https://bugzilla.mozilla.org/buglist.cgi?bug_id=1924108%2C1950780%2C1959367
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-28/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-31/'
    label: security@mozilla.org
tags:
  - nvd
epss: 0.00304
epssPercentile: 0.20945
ingestedAt: '2026-09-30T18:17:24.436Z'
---

## Overview

Memory safety bugs present in Firefox 137 and Thunderbird 137. 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 138 and Thunderbird 138.

## Affected

- `firefox < 138.0`
- `thunderbird < 138.0`

## Remediation

Upgrade past the affected range:

- `firefox 138.0`
- `thunderbird 138.0`