CVE-2026-72723
Received Received - Intake

Information Disclosure in Discourse via SiteSerializer

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: GitHub, Inc.

Description
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, SiteSerializer.anonymous_default_navigation_menu_tags serializes tags from SiteSetting.default_navigation_menu_tags without applying DiscourseTagging.filter_visible for the anonymous viewer. An unauthenticated user can retrieve restricted tag names and descriptions through /site.json when those tags are limited by inaccessible categories, category tag groups, or tag-group permissions. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.

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Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
CVE-2026-72723
EUVD
EUVD-2026-55660

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
discourse discourse to 2026.1.6 (exc)
discourse discourse to 2026.5.2 (exc)
discourse discourse to 2026.6.1 (exc)
discourse discourse to 2026.7.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

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Executive Summary

This vulnerability in Discourse allows unauthenticated users to access restricted tag names and descriptions through the /site.json endpoint. The issue occurs because the SiteSerializer.anonymous_default_navigation_menu_tags does not filter tags based on visibility for anonymous users, exposing tags that should be hidden due to category restrictions or permissions.

Detection Guidance

Check Discourse version with: bundle exec rails c -e production -p "puts Discourse::VERSION::STRING". If version is below 2026.1.6, 2026.5.2, 2026.6.1, or 2026.7.0, the system is vulnerable. Test for exposure by accessing /site.json and reviewing tag names/descriptions that should be restricted.

Impact Analysis

An attacker could exploit this to gather sensitive information about restricted tags, such as names and descriptions, which may reveal details about internal categories or permissions. This could aid in further attacks or expose confidential information.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, potentially violating GDPR's data protection principles or HIPAA's confidentiality requirements. Exposure of restricted tags may result in non-compliance with these regulations.

Mitigation Strategies

Upgrade Discourse to version 2026.1.6, 2026.5.2, 2026.6.1, or 2026.7.0 immediately. Verify the fix by checking /site.json no longer exposes restricted tags. Review and update category tag groups and permissions to ensure proper access controls.

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