Discourse: Hidden tag names leaked via category serializers
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.3epss 0.5%
exploitation probability
0.5%top 58% of all CVEs
observed exploitation
nono source reports it
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, restricted tag and tag-group names attached to publicly readable categories as allowed_tags, allowed_tag_groups, or required tag groups could leak to anonymous and unauthorized users through category and group endpoints. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Affected products
discourse · discourseReferences
https://github.com/discourse/discourse/releases/tag/v2026.1.5https://github.com/discourse/discourse/releases/tag/v2026.4.2https://github.com/discourse/discourse/releases/tag/v2026.5.1https://github.com/discourse/discourse/releases/tag/v2026.6.0https://github.com/discourse/discourse/security/advisories/GHSA-mwp7-572g-6qpx