CVE-2026-72722Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs
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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.
- CVSS
- 4.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- Weakness (CWE)
- CWE-862
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Aug 13, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
discourse discourse discourse:discourse (from the name) | before 2026.1.6; from 2026.5.0-latest, < 2026.5.2; from 2026.6.0-latest, < 2026.6.1; from 2026.7.0-latest, < 2026.7.0 | CNA record |
References
- https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4x-refsource-confirm
- https://github.com/discourse/discourse/pull/42091x-refsource-misc
- https://github.com/discourse/discourse/pull/42092x-refsource-misc
- https://github.com/discourse/discourse/pull/42093x-refsource-misc
- https://github.com/discourse/discourse/pull/42094x-refsource-misc
- https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31x-refsource-misc
- https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4x-refsource-misc
- https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191fx-refsource-misc
- https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1ax-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.