Memory safety bugs fixed in Firefox 137, Thunderbird 137, Firefox ESR 128.9, and Thunderbird 128.9
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.1epss 0.5%
exploitation probability
0.5%top 60% of all CVEs
observed exploitation
nono source reports it
Memory safety bugs present in Firefox 136, Thunderbird 136, Firefox ESR 128.8, and Thunderbird 128.8. 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 137, Firefox ESR 128.9, Thunderbird 137, and Thunderbird 128.9.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
References
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1850615%2C1932468%2C1942551%2C1951017%2C1951494https://lists.debian.org/debian-lts-announce/2025/04/msg00005.htmlhttps://www.mozilla.org/security/advisories/mfsa2025-20/https://www.mozilla.org/security/advisories/mfsa2025-22/https://www.mozilla.org/security/advisories/mfsa2025-23/https://www.mozilla.org/security/advisories/mfsa2025-24/