Out-of-bounds Read in Mozilla Firefox

CVE-2026-12298

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

Vulnerability class: Buffer Overflow

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N.

Affected products

Mozilla Firefox — versions 140.12, 152
Mozilla Thunderbird — versions 140.12, 152

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-12298?: CVE-2026-12298 is a medium-severity vulnerability in Mozilla Firefox, classified under Out-of-bounds Read. CVSS score: 5.4/10. Published 2026-06-16.
How severe is CVE-2026-12298?: Medium severity. CVSS v3 base score is 5.4 out of 10.