CVE-2026-9693 Mattermost thread memberships persist after team removal, exposing private channel thread metadata on re-invite

Mattermost versions 10.11.x = 10.11.20, 11.7.x = 11.7.5 Mattermost fails to remove thread membership records when a user is removed from or leaves a team, which allows a previously removed user who is later re-invited to the team to view private channel thread root post content and metadata via t...

PT-2026-76875

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.0 through 10.11.20 Mattermost versions 11.7.0 through 11.7.5 Description The software fails to remove thread membership records when a user leaves or is removed from a team. This allows a user who is subsequently...