CVE-2026-109776

Race condition in the XPCOM component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

• https://bugzilla.mozilla.org/show_bug.cgi?id=2069395
• https://www.mozilla.org/security/advisories/mfsa2026-106/
• https://www.mozilla.org/security/advisories/mfsa2026-108/
• https://www.mozilla.org/security/advisories/mfsa2026-109/
• https://www.mozilla.org/security/advisories/mfsa2026-110/