Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-72722
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-10 16:19:49 UTC
Updated2026-08-10 16:19:49 UTC
DescriptionDiscourse 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.

Risk And Classification

Primary CVSS: v3.1 4.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Problem Types: CWE-862 | CWE-862 CWE-862: Missing Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
3.1CNADECLARED4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Discourse Discourse affected < 2026.1.6 Not specified
CNA Discourse Discourse affected >= 2026.5.0-latest, < 2026.5.2 Not specified
CNA Discourse Discourse affected >= 2026.6.0-latest, < 2026.6.1 Not specified
CNA Discourse Discourse affected >= 2026.7.0-latest, < 2026.7.0 Not specified

References

ReferenceSourceLinkTags
github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52f... [email protected] github.com
github.com/discourse/discourse/pull/42093 [email protected] github.com
github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f2... [email protected] github.com
github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4 [email protected] github.com
github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e... [email protected] github.com
github.com/discourse/discourse/pull/42092 [email protected] github.com
github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b1... [email protected] github.com
github.com/discourse/discourse/pull/42091 [email protected] github.com
github.com/discourse/discourse/pull/42094 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report