CVE-2025-6436

Published: Jun 24, 2025Modified: Apr 13, 2026

8.1

Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitability: 2.2 / Impact: 5.9

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)

Description

Memory safety bugs present in Firefox 139 and Thunderbird 139. 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 140 and Thunderbird 140.

Affected (2)

Products: Mozilla: Firefox, Thunderbird

2 products

Configuration A

2 vulnerable

Vulnerable Software	Affected Versions
Mozilla Firefox	Before 140.0
Mozilla Thunderbird	Before 140.0

Related CWEs

Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

References (3)

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C1966187%2C1966505%2C1970764%2C1942930

Source: security@mozilla.org

Permissions Required

https://www.mozilla.org/security/advisories/mfsa2025-51/

Source: security@mozilla.org

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2025-54/

Source: security@mozilla.org

Vendor Advisory

Timeline

No history available yet.