---
id: CVE-2025-0242
title: >-
  Memory safety bugs present in Firefox 133, Thunderbird 133, Firefox ESR
  115.18, Firefox ESR 128.5, Thunderbird 115.18, and Thunderbird 128.5
summary: >-
  Memory safety bugs present in Firefox 133, Thunderbird 133, Firefox ESR
  115.18, Firefox ESR 128.5, Thunderbird 115.18, and Thunderbird 128.5. Some of
  these bugs showed evidence of memory corruption and we presume that with
  enough effort …
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-787
vendor: mozilla
product: firefox
affected:
  - firefox <= 115.19.0
  - firefox < 134.0
  - 'firefox >= 116.0, < 128.6.0'
  - thunderbird < 128.6.0
  - 'thunderbird >= 129.0, < 134.0'
patched:
  - firefox 128.6.0
  - thunderbird 134.0
published: '2025-01-07'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T19:10:01.007'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-0242'
references:
  - url: >-
      https://bugzilla.mozilla.org/buglist.cgi?bug_id=1874523%2C1926454%2C1931873%2C1932169
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-01/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-02/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-03/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-04/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-05/'
    label: security@mozilla.org
  - url: 'https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.1307
epssPercentile: 0.96233
ingestedAt: '2026-09-30T19:21:07.219Z'
---

## Overview

Memory safety bugs present in Firefox 133, Thunderbird 133, Firefox ESR 115.18, Firefox ESR 128.5, Thunderbird 115.18, and Thunderbird 128.5. 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 134, Firefox ESR 128.6, Firefox ESR 115.19, Thunderbird 134, and Thunderbird 128.6.

## Affected

- `firefox <= 115.19.0`
- `firefox < 134.0`
- `firefox >= 116.0, < 128.6.0`
- `thunderbird < 128.6.0`
- `thunderbird >= 129.0, < 134.0`

## Remediation

Upgrade past the affected range:

- `firefox 128.6.0`
- `thunderbird 134.0`