Memory Safety Bugs in Firefox ESR 140.11 and Thunderbird ESR 140.11 by Mozilla
CVE-2026-12327

Currently unrated

Key Information:

Vendor: Mozilla
Status: Firefox
Vendor: CVE Published:; 16 June 2026

What is CVE-2026-12327?

In various versions of Mozilla’s Firefox ESR and Thunderbird, memory safety vulnerabilities have been identified. These bugs expose the products to potential memory corruption, which could allow attackers to exploit the system and execute arbitrary code if sufficient effort is applied. Patches for these vulnerabilities have been released in newer versions, enhancing the security of the affected products.

Affected Version(s)

Firefox 140.12

Firefox 152

References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=2011842%2...

https://www.mozilla.org/security/advisories/mfsa2026-57/

https://www.mozilla.org/security/advisories/mfsa2026-58/

Download the Critical Vulnerability Management Cheat Sheet

Timeline

Vulnerability published
Jun 16, 2026
Vulnerability Reserved
Jun 15, 2026

Credit

Christian Holler, Jens Stutte, Nika Layzell, Randell Jesup, Tom Schuster and the Mozilla Fuzzing Team

CVE-2026-12327 Data

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