Discourse - Private Group Membership Inference via exclude_groups

Discourse 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contains an information disclosure caused by unauthenticated users observing directory results changes with the excludegroups parameter, letting attackers determine private group membership, exploit requires public access to user directory. id:...

CVE-2026-33425: Observable Discrepancy

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, unauthenticated users can determine whether a specific user is a member of a private group by observing changes in directory results when using the excludegroups parameter. Versions...