CVE-2025-1012 — A race during concurrent delazification could have led to a use-after-free.

Description

A race during concurrent delazification could have led to a use-after-free. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1939710
• https://www.mozilla.org/security/advisories/mfsa2025-07/
• https://www.mozilla.org/security/advisories/mfsa2025-08/
• https://www.mozilla.org/security/advisories/mfsa2025-09/
• https://www.mozilla.org/security/advisories/mfsa2025-10/
• https://www.mozilla.org/security/advisories/mfsa2025-11/
• https://lists.debian.org/debian-lts-announce/2025/02/msg00005.html
• https://lists.debian.org/debian-lts-announce/2025/02/msg00006.html