CVE-2025-5269 — Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10.

Description

Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox ESR 128.11 and Thunderbird 128.11.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1924108
• https://www.mozilla.org/security/advisories/mfsa2025-44/
• https://www.mozilla.org/security/advisories/mfsa2025-46/
• https://lists.debian.org/debian-lts-announce/2025/05/msg00043.html
• https://lists.debian.org/debian-lts-announce/2025/05/msg00046.html