Information disclosure in Discourse - CVE-2026-47264
Published: July 1, 2026
Vulnerability identifier: #VU136586
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-47264
CWE-ID: CWE-200
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Civilized Discourse Construction Kit, Inc.
Affected software:
Discourse
Discourse
Detailed vulnerability description
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to exposure of sensitive information in DetailedTagSerializer#tag_group_names when handling tag info requests. A remote attacker can send a request to TagsController#info to disclose sensitive information.
Only instances with SiteSetting.tags_listed_by_group enabled are vulnerable, and the issue can expose names of tag groups restricted to specific user groups or non-visible categories.
How to mitigate CVE-2026-47264
Install security update from vendor's website.