---
id: CVE-2026-12306
title: Memory safety bug fixed in Thunderbird 152
summary: >-
  Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in
  Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cvssSource: adp
vendor: Mozilla
product: Firefox
affected:
  - Firefox
  - Thunderbird
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-06-16T17:36:09.015688Z'
published: '2026-06-16'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T13:50:01.698Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-12306'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=2037323'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-57/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-58/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-60/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-61/'
tags:
  - cve.org
epss: 0.00261
epssPercentile: 0.16777
ingestedAt: '2026-10-21T13:57:01.107Z'
---

## Overview

Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

## Affected

- `Firefox`
- `Thunderbird`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.