CVE-2026-5735

EUVD-2026-19616
Memory safety bugs present in Firefox 149.0.1 and Thunderbird 149.0.1. 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 affects Firefox < 149.0.2 and Thunderbird < 149.0.2.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
9.8 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Affected Products (NVD)
VendorProductVersion
mozillafirefox
𝑥
< 149.0.2
mozillathunderbird
𝑥
< 149.0.2
𝑥
= Vulnerable software versions
Debian logo
Debian Releases
Debian Product
Codename
firefox
sid
vulnerable
Common Weakness Enumeration
References
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2025475%2C2025477
https://www.mozilla.org/security/advisories/mfsa2026-25/
https://www.mozilla.org/security/advisories/mfsa2026-28/