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.
https://www.mozilla.org/security/advisories/mfsa2024-14/
https://www.mozilla.org/security/advisories/mfsa2024-13/
https://www.mozilla.org/security/advisories/mfsa2024-12/
https://lists.debian.org/debian-lts-announce/2024/03/msg00028.html
https://lists.debian.org/debian-lts-announce/2024/03/msg00022.html