CVE-2026-72722
MediumCVSS 4.3Exploitation Probability (EPSS)
Low risk25th percentile - higher than 25% of all known CVEs
Summary
Discourse prior to versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0 in TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup does 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.
Risk Assessment
Disclosure of titles and slugs of restricted content may compromise confidentiality and allow an attacker to gain information about non-public discussions.
Recommendation
Update Discourse to version 2026.1.6, 2026.5.2, 2026.6.1, or 2026.7.0.
Original NVD description (English source)
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.