---
id: CVE-2026-12300
title: Memory safety bug fixed in Thunderbird 152
summary: >-
  Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in
  Firefox 152 and Thunderbird 152.
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: '2026-06-16T17:26:03.760142Z'
published: '2026-06-16'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T13:50:00.281Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-12300'
references:
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1704114'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-57/'
  - url: 'https://www.mozilla.org/security/advisories/mfsa2026-60/'
tags:
  - cve.org
epss: 0.00252
epssPercentile: 0.15717
ingestedAt: '2026-10-21T13:57:01.107Z'
---

## Overview

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

## Affected

- `Firefox`
- `Thunderbird`

## Remediation

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