By monitoring the time certain operations take, an attacker could have guessed which external protocol handlers were functional on a user’s system. This vulnerability affects Firefox < 127, Firefox ESR < 115.12, and Thunderbird < 115.12.
bugzilla.mozilla.org/show_bug.cgi?id=1883693
lists.debian.org/debian-lts-announce/2024/06/msg00000.html
lists.debian.org/debian-lts-announce/2024/06/msg00010.html
www.mozilla.org/security/advisories/mfsa2024-25/
www.mozilla.org/security/advisories/mfsa2024-26/
www.mozilla.org/security/advisories/mfsa2024-28/