Vulnerability · Published Jul 9, 2026 · Assigned by GitHub_M

CVE-2026-49256Discourse: Hidden tag names leaked via category serializers

Medium 6.3

In plain English

A medium-severity information exposure in discourse from discourse. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities).

Severity (CVSS 4.0)6.3Medium

Exploit odds (30 days)0.5%top 56.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
discourse	discourse	>= 2026.1.0-latest, < 2026.1.5>= 2026.4.0-latest, < 2026.4.2>= 2026.5.0-latest, < 2026.5.1

Weakness: CWE-200 · Vector: 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

References

https://github.com/discourse/discourse/security/advisories/GHSA-mwp7-572g-6qpx x_refsource_CONFIRM
https://github.com/discourse/discourse/releases/tag/v2026.1.5 x_refsource_MISC
https://github.com/discourse/discourse/releases/tag/v2026.4.2 x_refsource_MISC
https://github.com/discourse/discourse/releases/tag/v2026.5.1 x_refsource_MISC
https://github.com/discourse/discourse/releases/tag/v2026.6.0 x_refsource_MISC