CVE-2023-32318 in Server
Summary
by MITRE • 05/26/2023
Nextcloud server provides a home for data. A regression in the session handling between Nextcloud Server and the Nextcloud Text app prevented a correct destruction of the session on logout if cookies were not cleared manually. After successfully authenticating with any other account the previous session would be continued and the attacker would be authenticated as the previously logged in user. It is recommended that the Nextcloud Server is upgraded to 25.0.6 or 26.0.1.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/27/2023
The vulnerability identified as CVE-2023-32318 represents a critical session management flaw within the Nextcloud server ecosystem that undermines the fundamental security assumptions of user authentication and authorization. This regression specifically affects the interaction between the core Nextcloud server and the Nextcloud Text application, creating a persistent security risk that allows unauthorized access to user sessions. The flaw manifests when users log out of the system, as the session destruction mechanism fails to properly terminate the user's authenticated state, particularly when browser cookies are not manually cleared by the user.
The technical nature of this vulnerability stems from improper session handling logic that fails to completely invalidate session tokens upon user logout. According to CWE-613, this represents an inadequate session management issue where session resources are not properly destroyed, creating a window of opportunity for session hijacking attacks. The vulnerability operates through a session fixation pattern where the previous user's session remains active and accessible, allowing an attacker to continue using the same session identifier even after a legitimate user has logged out. This regression essentially creates a persistent authentication context that bypasses normal session termination procedures.
The operational impact of this vulnerability is significant as it enables attackers to seamlessly transition between user accounts without proper authentication. When a user logs out and another individual subsequently logs in, the system fails to properly invalidate the previous session, allowing the attacker to continue operating under the previous user's authenticated context. This creates a persistent security threat where session tokens remain valid and usable, effectively providing unauthorized access to sensitive data and system resources. The vulnerability affects the core authentication and authorization mechanisms that protect user data within the Nextcloud environment, potentially exposing personal files, documents, and system configurations to unauthorized access.
This security weakness directly violates several principles of secure session management as defined in the OWASP Top Ten and NIST SP 800-63 standards, particularly concerning session invalidation and proper authentication state management. The issue demonstrates a failure in implementing proper session lifecycle management where logout operations do not effectively terminate all associated session resources. The vulnerability creates a condition where session tokens persist beyond their intended validity period, allowing attackers to leverage previously valid sessions for unauthorized access. Organizations using Nextcloud server installations should immediately implement the recommended upgrades to version 25.0.6 or 26.0.1 to address this regression and restore proper session termination behavior. Additionally, administrators should consider implementing additional monitoring and session management controls to detect and prevent unauthorized session reuse, particularly in environments where multiple users access shared systems or where session hijacking attacks are a concern. The vulnerability also highlights the importance of thorough regression testing when implementing application updates, as this issue represents a clear case where a code change inadvertently broke existing session management functionality.