Nextcloud Deck before 1.0.2 suffers from an insecure direct object reference (IDOR) vulnerability that permits users with a duplicate user identifier to access deck data of a previous deleted user.
Improper neutralization of file names, conversation names and board names in Nextcloud Server 16.0.3, Nextcloud Talk 6.0.3 and Nextcloud Deck 0.6.5 causes an XSS when linking them with each others in a project.