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.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact Low

Integrity Impact None

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
discourse discourse affected
Version Status Constraints
< 2026.1.6 affected —
>= 2026.5.0-latest, < 2026.5.2 affected —
>= 2026.6.0-latest, < 2026.6.1 affected —
>= 2026.7.0-latest, < 2026.7.0 affected —

No data.

No data.

No data.

Project Subscriptions

No data.

Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31 cve-icon
https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4 cve-icon
https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191f cve-icon
https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1a cve-icon
https://github.com/discourse/discourse/pull/42091 cve-icon
https://github.com/discourse/discourse/pull/42092 cve-icon
https://github.com/discourse/discourse/pull/42093 cve-icon
https://github.com/discourse/discourse/pull/42094 cve-icon
https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4 cve-icon
History

Mon, 10 Aug 2026 16:15:00 +0000

Type Values Removed Values Added
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.
Title Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs
Weaknesses CWE-862
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-10T15:54:35.907Z

Reserved: 2026-08-10T13:48:09.545Z

Link: CVE-2026-72722

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses