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Details of issue NIXPKGS-2026-0720

NIXPKGS-2026-0720
published 3 months ago
Permalink CVE-2026-31869
updated 3 months ago by @LeSuisse Activity log
  • Created suggestion 3 months ago
  • @LeSuisse ignored
    5 packages
    • discourse-mail-receiver
    • python312Packages.pydiscourse
    • python313Packages.pydiscourse
    • python314Packages.pydiscourse
    • grafanaPlugins.grafana-discourse-datasource
    3 months ago
  • @LeSuisse accepted 3 months ago
  • @LeSuisse published on GitHub 3 months ago
Discourse: Composer mentions endpoint leaks hidden group membership through PM `allowed_names` check

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the ComposerController#mentions endpoint reveals hidden group membership to any authenticated user who can message the group. By supplying allowed_names referencing a hidden-membership group and probing arbitrary usernames, an attacker can infer membership based on whether user_reasons returns "private" for a given user. This bypasses group member-visibility controls. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. To work around this issue, restrict the messageable policy of any hidden-membership group to staff or group members only, so untrusted users cannot reach the vulnerable code path.

Affected products

discourse
  • ==>= 2026.1.0-latest, < 2026.1.2
  • === 2026.3.0-latest
  • ==>= 2026.2.0-latest, < 2026.2.1

Matching in nixpkgs

Ignored packages (5)

Package maintainers

Upstream advisory: https://github.com/discourse/discourse/security/advisories/GHSA-5f9h-vp7v-7vq5