CVE-2026-2807: Memory safety bugs fixed in Firefox 148 and Thunderbird 148

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-24 · updated 2026-07-15
Weakness: CWE-787

Description

Memory safety bugs present in Firefox 147 and Thunderbird 147. 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 148 and Thunderbird 148.

Affected products

Mozilla Firefox: before 148.0 — fixed in 148.0
Mozilla Thunderbird: before 148.0 — fixed in 148.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 148.0; Mozilla Thunderbird 148.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1756056%2C1999402%2C2004872%2C2006037%2C2012855
https://www.mozilla.org/security/advisories/mfsa2026-13/
https://www.mozilla.org/security/advisories/mfsa2026-16/
https://access.redhat.com/security/cve/CVE-2026-2807
https://bugzilla.redhat.com/show_bug.cgi?id=2442296
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2807.json

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