CVE-2026-47264
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk10th percentile — higher than 10% of all known CVEs
Summary
Discourse is an open-source discussion platform with a vulnerability in versions from 2026.1.0 to before 2026.1.4, from 2026.3.0 to before 2026.3.1, and from 2026.4.0 to before 2026.4.1. The DetailedTagSerializer#tag_group_names function returned all tag groups a tag belonged to without considering the user's visibility, allowing anonymous and unprivileged users to access the names of tag groups restricted to specific user groups.
Risk Assessment
The organization may be exposed to the disclosure of information about tag groups intended only for selected users, which could lead to privacy breaches and data security issues.
Recommendation
It is recommended to update Discourse to versions 2026.1.4, 2026.3.1, 2026.4.1, or 2026.5.0-latest.1 to mitigate this vulnerability.
Original NVD description (English source)
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#tag_group_names returned every tag group a tag belonged to without filtering against the requesting user's visibility. With SiteSetting.tags_listed_by_group enabled, anonymous and unprivileged users hitting TagsController#info (which is exempt from requires_login) 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.