CVE-2026-57447 in Doc Categories Plugin
Summary
by MITRE • 10/16/2026
Discourse Doc Categories is a plugin for organizing Discourse topics as documentation. Prior to the verified source fix, the doc category index refresh resolves linked titles for private messages or restricted category topics without enforcing the viewer's authorization. A user who can edit the index topic can use this behavior to learn titles that the user is not authorized to view, although the advisory does not establish access to topic contents. This vulnerability is addressed by commit b15d4de02ad29d7c9525346afee51fef4a2c605a.
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Analysis
by VulDB Data Team • 10/16/2026
The Discourse Doc Categories plugin serves as a specialized tool for organizing topics within the Discourse forum software into structured documentation categories, enhancing usability for knowledge bases and technical support systems. A critical security flaw was identified in this plugin prior to its verified source fix, specifically concerning the mechanism used to refresh the doc category index. This vulnerability stems from an improper authorization check during the resolution of linked titles for private messages or topics located within restricted categories. When the system attempts to update the documentation index by resolving these links, it fails to enforce the viewer's specific access permissions against the target content. Consequently, the process retrieves and displays title information regardless of whether the requesting user has legitimate rights to view that particular topic.
This authorization bypass allows any authenticated user who possesses edit privileges for a doc category index topic to exploit this behavior. By triggering an index refresh or similar action, such a user can enumerate titles associated with private messages or restricted topics they are otherwise denied access to. While the vulnerability is limited in scope and does not grant direct read access to the actual content of these protected topics, it still constitutes a significant information disclosure risk. The exposure of topic titles can reveal sensitive project names, internal discussion subjects, or confidential issue tracking identifiers that were intended to remain hidden from unauthorized personnel. This leakage aids attackers in reconnaissance efforts by providing contextual clues about organizational structure and ongoing activities without triggering standard access control alerts.
From a classification perspective, this vulnerability aligns with CWE-200: Information Exposure, as it involves the unintended disclosure of sensitive information through improper authorization controls. It also relates to CWE-862: Missing Authorization, highlighting the failure to enforce proper checks before accessing resources associated with private or restricted categories. In terms of offensive security frameworks, this behavior corresponds to ATT&CK technique T1087: Account Discovery, where an adversary gathers information about accounts and services within a network environment through enumeration techniques. The exploitation relies on the attacker leveraging existing permissions for index editing rather than breaking into higher-privilege systems, making it a subtle but effective method for gathering intelligence in targeted attacks against organizations using this plugin.
To mitigate this vulnerability, administrators must ensure that the Discourse Doc Categories plugin is updated to include commit b15d4de02ad29d7c9525346afee51fef4a2c605a or any subsequent patches released by the maintainers. This fix enforces strict authorization checks during the title resolution process, ensuring that only users with explicit permission to view a topic can have its details included in the doc category index refresh operation. Beyond applying software updates, organizations should review their plugin configurations and restrict edit access for documentation indexes to trusted administrators who require such privileges for legitimate maintenance tasks. Regular auditing of user permissions within private or restricted categories further reduces the attack surface by limiting the number of users capable of triggering potentially exploitable actions related to sensitive content metadata.