Using a markup injection an attacker could have stolen nonce values. This could have been used to bypass strict content security policies. This vulnerability affects Firefox < 124, Firefox ESR < 115.9, and Thunderbird < 115.9.
bugzilla.mozilla.org/show_bug.cgi?id=1871112
lists.debian.org/debian-lts-announce/2024/03/msg00022.html
lists.debian.org/debian-lts-announce/2024/03/msg00028.html
www.mozilla.org/security/advisories/mfsa2024-12/
www.mozilla.org/security/advisories/mfsa2024-13/
www.mozilla.org/security/advisories/mfsa2024-14/