CVE-2023-26041 in Talk
Summary
by MITRE • 02/27/2023
Nextcloud Talk is a fully on-premises audio/video and chat communication service. When cron jobs were misconfigured and therefore messages are not expired, the API would still return them while they were then hidden by the frontend code. It is recommended that the Nextcloud Talk is upgraded to 15.0.3. There are no workaround available.
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Analysis
by VulDB Data Team • 03/26/2023
The vulnerability identified as CVE-2023-26041 affects Nextcloud Talk, a comprehensive on-premises communication platform that provides audio/video conferencing and chat capabilities. This issue stems from a misconfiguration in the cron job scheduling mechanism that governs message expiration within the system. The flaw represents a critical inconsistency between the backend data management and frontend presentation layers, creating a scenario where expired messages remain accessible through the application programming interface despite being visually hidden from user interfaces.
The technical implementation of this vulnerability involves a disconnect in the message lifecycle management process. When cron jobs responsible for cleaning up expired messages fail to execute properly due to misconfiguration, the system maintains these messages in its database while simultaneously employing frontend JavaScript code to conceal them from user displays. This creates a security risk where unauthorized parties could potentially access sensitive communication data through API endpoints that should logically return only active messages. The vulnerability manifests as a data exposure issue where the API layer continues to serve expired content while the presentation layer merely hides it visually.
From an operational perspective, this vulnerability compromises the integrity of the communication system's data lifecycle management. The misconfigured cron jobs create a persistent state where expired messages exist in the database but are not properly removed, leading to potential information leakage. Security researchers have identified this as a case of improper data handling where the system fails to maintain consistent state between its database and application interfaces. The vulnerability affects the confidentiality and integrity of communication data within Nextcloud Talk deployments, particularly in environments where message retention policies are critical for compliance and privacy requirements.
The recommended remediation involves upgrading to Nextcloud Talk version 15.0.3, which addresses the underlying cron job configuration issues and ensures proper message expiration mechanisms. This upgrade resolves the fundamental flaw in the system's automated cleanup processes that caused the data inconsistency. Organizations should implement comprehensive testing procedures to verify that cron jobs are properly configured and executing as expected after the upgrade. The absence of available workarounds underscores the critical nature of this vulnerability, as administrators cannot implement temporary fixes while maintaining system security. This vulnerability aligns with CWE-200, which addresses information exposure, and represents a specific implementation of improper data handling within communication systems. The flaw also intersects with ATT&CK technique T1566, which covers credential access through improper access control mechanisms, as expired messages may contain sensitive information that should not remain accessible beyond their intended retention periods. Organizations should also consider implementing monitoring solutions to detect anomalous cron job execution patterns and ensure proper message lifecycle management across their Nextcloud deployments.