CVE-2026-72722

MEDIUM 4.3

Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs

CVSS Score

4.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-862
Vendor	discourse
Product	discourse
Published	Aug 10, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Affected Versions

discourse / discourse

< 2026.1.6 >= 2026.5.0-latest, < 2026.5.2 >= 2026.6.0-latest, < 2026.6.1 >= 2026.7.0-latest, < 2026.7.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗