JavaScript code running while transforming a document with the XSLTProcessor could lead to a use-after-free. This vulnerability affects Firefox < 137, Firefox ESR < 115.22, Firefox ESR < 128.9, Thunderbird < 137, and Thunderbird < 128.9.
https://www.mozilla.org/security/advisories/mfsa2025-24/
https://www.mozilla.org/security/advisories/mfsa2025-23/
https://www.mozilla.org/security/advisories/mfsa2025-22/
https://www.mozilla.org/security/advisories/mfsa2025-21/