CVE-2025-66546

Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.19, 5.5.6, and 6.0.1, the calendar app allowed blindly booking appointments with a squential ID without known the appointment token. This vulnerability is fixed in 4.7.19, 5.5.6, and 6.0.1.

More information : https://github.com/nextcloud/calendar/commit/f41650c3681fc4a4130eb883f5c0899c011326b3