CVE-2022-21642 in Discourse
Summary
by MITRE • 01/05/2022
Discourse is an open source platform for community discussion. In affected versions when composing a message from topic the composer user suggestions reveals whisper participants. The issue has been patched in stable version 2.7.13 and beta version 2.8.0.beta11. There is no workaround for this issue and users are advised to upgrade.
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Analysis
by VulDB Data Team • 01/09/2022
The vulnerability identified as CVE-2022-21642 affects Discourse, an open source community discussion platform that serves millions of users worldwide. This security flaw represents a critical privacy and information disclosure issue within the platform's message composition functionality. The vulnerability specifically manifests when users are composing messages within topic threads, where the system's user suggestion feature inadvertently exposes participants who were designated as whisper recipients. This represents a significant breach of intended communication privacy boundaries within the platform's design.
The technical nature of this vulnerability stems from improper access control and privilege escalation within the composer interface. When users attempt to compose messages and utilize the auto-suggestion feature, the system fails to properly filter user lists based on their communication permissions. This flaw allows unauthorized exposure of whisper participants who should only be visible to specific users or moderators. The vulnerability exists in the client-side rendering logic that handles user suggestions and does not adequately validate or restrict access to user data based on their communication context within the platform. This type of flaw commonly maps to CWE-284 Access Control Issues and can be categorized under ATT&CK technique T1078 Valid Accounts for privilege escalation through improper access control mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally undermines the trust and privacy expectations within community discussions. Whisper participants are typically designated as private recipients for sensitive conversations, and their exposure through the suggestion system creates potential for unauthorized access to private communications. This issue particularly affects platforms where sensitive discussions, moderation communications, or private community matters are conducted through whisper features. The vulnerability affects all users who can access the composer interface, making it a widespread concern across any Discourse installation that utilizes whisper functionality. Attackers could exploit this vulnerability to gain insights into private communication patterns and potentially identify users who are part of sensitive discussions.
Organizations and community administrators running Discourse installations should immediately implement the recommended upgrade path to versions 2.7.13 or 2.8.0.beta11 to remediate this vulnerability. The lack of a viable workaround means that the only effective mitigation strategy is the software upgrade process, which addresses the root cause in the composer user suggestion functionality. Security teams should conduct thorough testing of the upgraded versions to ensure the fix properly addresses all edge cases within the user suggestion system. Additionally, administrators should review their existing communication patterns and user permissions to identify any potential misuse of the vulnerability before the patch was applied. The vulnerability highlights the importance of proper access control implementation in web-based community platforms and serves as a reminder of the critical nature of privacy controls in collaborative software environments.