CVE-2026-16047

Mattermost versions 11.7.x = 11.7.6, 10.11.x = 10.11.21, 11.8.x = 11.8.3 fail to validate that users have read access to a channel before linking a board to it, which allows an authenticated attacker to discover the membership of private channels on the same team via creating, patching, importing...

PT-2026-63292

Name of the Vulnerable Software and Affected Versions Gitea affected versions not specified Description The REST API exposes organization membership of public members within a private organization. An unauthorized user can determine if a specific user is a member of a private organization by...

Improper authorisation of members discloses room membership to non-members

Impact Unauthorised users can access the membership list of members, with their display names of a room if they know the ID of the room. The vulnerability is limited to rooms with shared history visibility. Furthermore, the unauthorised user must be using an account on a vulnerable homeserver tha...

CVE-2021-39164 Improper authorisation of /members discloses room membership to non-members

Matrix is an ecosystem for open federated Instant Messaging and Voice over IP. In versions 1.41.0 and prior, unauthorised users can access the membership list of members, with their display names of a room if they know the ID of the room. The vulnerability is limited to rooms with shared history...

CVE-2005-0080

The 55optionstraceback.dpatch patch for mailman 2.1.5 in Ubuntu 4.10 displays a different error message depending on whether the e-mail address is subscribed to a private list, which allows remote attackers to determine the list membership for a given e-mail address...