CVE-2025-4091: Memory Safety Bugs Present
Source GCVE Database
Not known to be exploited · CVSS 6.5 Medium.
Data as of 29 Oct 2026, 22:52 UTC
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 29 Apr 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
Description
Memory safety bugs present in Firefox 137, Thunderbird 137, Firefox ESR 128.9, and Thunderbird 128.9. 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 < 138, Firefox ESR < 128.10, Thunderbird < 138, and Thunderbird ESR < 128.10.
References
- nvd.nist.gov/vuln/detail/CVE-2025-4091 (opens in a new tab)
- bugzilla.mozilla.org/buglist.cgi?bug_id=1951161%2C1952105 (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00024.html (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-28 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-29 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-31 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2025-32 (opens in a new tab)