Use-after-free in the Layout: Text and Fonts component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.
https://www.mozilla.org/security/advisories/mfsa2026-24/
https://www.mozilla.org/security/advisories/mfsa2026-23/
https://www.mozilla.org/security/advisories/mfsa2026-22/
https://www.mozilla.org/security/advisories/mfsa2026-21/