SOGo before 2.3.12 and 3.x before 3.1.1 does not restrict access to the UID and DTSTAMP attributes, which allows remote authenticated users to obtain sensitive information about appointments with the "View the Date & Time" restriction, as demonstrated by correlating UIDs and DTSTAMPs between all users.
https://sogo.nu/bugs/view.php?id=3696
https://github.com/inverse-inc/sogo/commit/875a4aca3218340fd4d3141950c82c2ff45b343d
https://github.com/inverse-inc/sogo/commit/717f45f640a2866b76a8984139391fae64339225