---
id: CVE-2025-1016
title: >-
  Memory safety bugs present in Firefox 134, Thunderbird 134, Firefox ESR
  115.19, Firefox ESR 128.6, Thunderbird 115.19, and Thunderbird 128.6
summary: >-
  Memory safety bugs present in Firefox 134, Thunderbird 134, Firefox ESR
  115.19, Firefox ESR 128.6, Thunderbird 115.19, and Thunderbird 128.6. Some of
  these bugs showed evidence of memory corruption and we presume that with
  enough effort …
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-787
  - CWE-787
vendor: mozilla
product: firefox
affected:
  - firefox < 115.20.0
  - firefox < 135.0
  - 'firefox >= 128.1.0, < 128.7.0'
  - 'thunderbird >= 128.0.1, < 128.7.0'
  - 'thunderbird >= 131.0, < 135.0'
patched:
  - firefox 128.7.0
  - thunderbird 135.0
published: '2025-02-04'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T19:10:01.007'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-1016'
references:
  - url: >-
      https://bugzilla.mozilla.org/buglist.cgi?bug_id=1936601%2C1936844%2C1937694%2C1938469%2C1939583%2C1940994
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-07/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-08/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-09/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-10/'
    label: security@mozilla.org
  - url: 'https://www.mozilla.org/security/advisories/mfsa2025-11/'
    label: security@mozilla.org
  - url: 'https://lists.debian.org/debian-lts-announce/2025/02/msg00006.html'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00592
epssPercentile: 0.46276
ingestedAt: '2026-09-30T19:21:07.224Z'
---

## Overview

Memory safety bugs present in Firefox 134, Thunderbird 134, Firefox ESR 115.19, Firefox ESR 128.6, Thunderbird 115.19, and Thunderbird 128.6. 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 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

## Affected

- `firefox < 115.20.0`
- `firefox < 135.0`
- `firefox >= 128.1.0, < 128.7.0`
- `thunderbird >= 128.0.1, < 128.7.0`
- `thunderbird >= 131.0, < 135.0`

## Remediation

Upgrade past the affected range:

- `firefox 128.7.0`
- `thunderbird 135.0`