CVE-2026-47264: Discourse: Don't leak restricted tag group names via tag info
Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, DetailedTagSerializer#taggroupnames returned every tag group a tag belonged to without filtering against the requesting user's visibility. With SiteSetting.tagslistedbygroup enabled, anonymous and unprivileged users hitting TagsController#info (which is exempt from requireslogin) could read the names of tag groups restricted to specific user groups or non-visible categories. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Discourseto a version that resolves this vulnerability.Fixed in 2026.1.4 - Upgrade
Upgrade
Discourseto a version that resolves this vulnerability.Fixed in 2026.3.1 - Upgrade
Upgrade
Discourseto a version that resolves this vulnerability.Fixed in 2026.4.1 - Upgrade
Upgrade
Discourseto a version that resolves this vulnerability.Fixed in 2026.5.0-latest.1 - Configuration
Disable SiteSetting.tags_listed_by_group to prevent anonymous and unprivileged users from seeing restricted tag group names until you can upgrade to a patched version.
Discourse SiteSetting.tags_listed_by_group = false
Event History
Frequently Asked Questions
What is the severity of CVE-2026-47264?
CVE-2026-47264 has a medium severity rating of 5.3.
How do I fix CVE-2026-47264?
To fix CVE-2026-47264, update Discourse to version 2026.1.4, 2026.3.1, or 2026.4.1 or later.
What type of vulnerability is CVE-2026-47264?
CVE-2026-47264 is classified as an information leak vulnerability.
What versions of Discourse are affected by CVE-2026-47264?
CVE-2026-47264 affects Discourse versions from 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1.
What is the impact of CVE-2026-47264?
The impact of CVE-2026-47264 is that it can leak restricted tag group names that should not be visible to the requesting user.