Description
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see? checks when processing internal links. An authenticated user can submit links to restricted topics, private messages, or hidden posts and receive canonicalized slugs or titles in the composer_messages duplicate_lookup response even though the targets are not visible to that user. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
discourse discourse
< 2026.1.6affected>= 2026.5.0-latest, < 2026.5.2affected>= 2026.6.0-latest, < 2026.6.1affected>= 2026.7.0-latest, < 2026.7.0affected
References
- https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4 ↗
- https://github.com/discourse/discourse/pull/42091 ↗
- https://github.com/discourse/discourse/pull/42092 ↗
- https://github.com/discourse/discourse/pull/42093 ↗
- https://github.com/discourse/discourse/pull/42094 ↗
- https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31 ↗
- https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4 ↗
- https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191f ↗
- https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1a ↗