Through a series of API calls and redirects, an attacker-controlled alert dialog could have been displayed on another website (with the victim website's URL shown). This vulnerability affects Firefox < 123, Firefox ESR < 115.8, and Thunderbird < 115.8.
https://www.mozilla.org/security/advisories/mfsa2024-07/
https://www.mozilla.org/security/advisories/mfsa2024-06/
https://www.mozilla.org/security/advisories/mfsa2024-05/
https://lists.debian.org/debian-lts-announce/2024/03/msg00001.html
https://lists.debian.org/debian-lts-announce/2024/03/msg00000.html