Memory Safety Vulnerability in Firefox Browser by Mozilla
CVE-2026-12308

5.3MEDIUM

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
16 June 2026

What is CVE-2026-12308?

A memory safety vulnerability was identified in Mozilla's Firefox, specifically in version 152 and Firefox ESR 140.12. This flaw could potentially allow for unauthorized access or manipulation of memory, leading to execution of arbitrary code. Mozilla has addressed the issue in the respective versions, ensuring enhanced security for users. It is highly recommended for users to update their browsers to the latest versions to mitigate any potential risks associated with this vulnerability.

Affected Version(s)

Firefox 140.12

Firefox 152

Thunderbird 140.12

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2038302
https://www.mozilla.org/security/advisories/mfsa2026-57/
https://www.mozilla.org/security/advisories/mfsa2026-58/

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Mihalis Haatainen
.