CVE-2026-47264
Received Received - Intake
Information Disclosure in Discourse via Tag Groups

Publication date: 2026-06-12

Last updated on: 2026-06-12

Assigner: GitHub, Inc.

Description
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.
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Meta Information
Published
2026-06-12
Last Modified
2026-06-12
Generated
2026-06-13
AI Q&A
2026-06-13
EPSS Evaluated
N/A
NVD
CVE-2026-47264
Affected Vendors & Products
Showing 7 associated CPEs
Vendor Product Version / Range
discourse discourse From 2026.1.0 (inc) to 2026.1.4 (exc)
discourse discourse From 2026.3.0 (inc) to 2026.3.1 (exc)
discourse discourse From 2026.4.0 (inc) to 2026.4.1 (exc)
discourse discourse to 2026.1.4 (inc)
discourse discourse to 2026.3.1 (inc)
discourse discourse to 2026.4.1 (inc)
discourse discourse to 2026.5.0 (inc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-200 The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
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Executive Summary

This vulnerability affects the Discourse open-source discussion platform in certain versions before 2026.1.4, 2026.3.1, and 2026.4.1. The issue is that the DetailedTagSerializer#tag_group_names function returned all tag groups a tag belonged to without checking if the requesting user had permission to see them. When the SiteSetting.tags_listed_by_group setting was enabled, anonymous and unprivileged users could access the TagsController#info endpoint, which does not require login, and read the names of tag groups that were supposed to be restricted to specific user groups or hidden categories.

Impact Analysis

This vulnerability can lead to unauthorized information disclosure. Specifically, users who are not logged in or do not have the necessary privileges can see the names of tag groups that are meant to be restricted. This could reveal sensitive organizational structures or categorization schemes that were intended to be hidden, potentially aiding attackers in understanding the platform's internal setup or bypassing other security controls.

Mitigation Strategies

To mitigate this vulnerability, you should upgrade your Discourse installation to one of the patched versions: 2026.1.4, 2026.3.1, 2026.4.1, or 2026.5.0-latest.1.

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