Information disclosure, privilege escalation in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
https://www.mozilla.org/security/advisories/mfsa2026-110/
https://www.mozilla.org/security/advisories/mfsa2026-109/
https://www.mozilla.org/security/advisories/mfsa2026-108/
https://www.mozilla.org/security/advisories/mfsa2026-106/