A type check was missing when handling fonts in PDF.js, which would allow arbitrary JavaScript execution in the PDF.js context. This vulnerability affects Firefox < 126, Firefox ESR < 115.11, and Thunderbird < 115.11.
bugzilla.mozilla.org/show_bug.cgi?id=1893645
lists.debian.org/debian-lts-announce/2024/05/msg00010.html
lists.debian.org/debian-lts-announce/2024/05/msg00012.html
www.mozilla.org/security/advisories/mfsa2024-21/
www.mozilla.org/security/advisories/mfsa2024-22/
www.mozilla.org/security/advisories/mfsa2024-23/