CVE-2026-12326: Memory safety bugs fixed in Firefox 152 and Thunderbird 152

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-16 · updated 2026-10-26
Weakness: CWE-119

Description

Memory safety bugs present in Firefox 151 and Thunderbird 151. 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 152 and Thunderbird 152.

Affected products

Mozilla Firefox: before 152.0.0 — fixed in 152.0.0
Mozilla Thunderbird: before 152.0.0 — fixed in 152.0.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 152.0.0; Mozilla Thunderbird 152.0.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1767455%2C2004308%2C2024445%2C2028182%2C2029765%2C2029883%2C2030110%2C2030149%2C2030366%2C2030374%2C2030564%2C2031120%2C2033411%2C2038695%2C2042465%2C2042781%2C2042907
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2021955%2C2025960%2C2029066%2C2029403%2C2029435%2C2029803%2C2030570%2C2030573%2C2032264%2C2033234%2C2034816%2C2035907%2C2035963%2C2036895%2C2036898%2C2036907%2C2036909%2C2036928%2C2036931%2C2036932%2C2036934%2C2039238%2C2039463
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2039050%2C2042718%2C2042760%2C2044831%2C2045307%2C2045398%2C2045516%2C2045572%2C2041741%2C2044433
https://www.mozilla.org/security/advisories/mfsa2026-57/
https://www.mozilla.org/security/advisories/mfsa2026-60/
https://access.redhat.com/security/cve/CVE-2026-12326
https://bugzilla.redhat.com/show_bug.cgi?id=2489222
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-12326.json

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