CVE-2024-37313 in Server
Summary
by MITRE • 06/14/2024
Nextcloud server is a self hosted personal cloud system. Under some circumstance it was possible to bypass the second factor of 2FA after successfully providing the user credentials. It is recommended that the Nextcloud Server is upgraded to 26.0.13, 27.1.8 or 28.0.4 and Nextcloud Enterprise Server is upgraded to 21.0.9.17, 22.2.10.22, 23.0.12.17, 24.0.12.13, 25.0.13.8, 26.0.13, 27.1.8 or 28.0.4.
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Analysis
by VulDB Data Team • 09/27/2025
The vulnerability identified as CVE-2024-37313 represents a critical security flaw in Nextcloud server implementations that undermines the fundamental security principle of multi-factor authentication. This weakness allows attackers to bypass the second factor of authentication after successfully obtaining valid user credentials through various means including credential theft, brute force attacks, or social engineering techniques. The vulnerability specifically affects the authentication flow within Nextcloud's 2FA system, creating a scenario where successful authentication with primary credentials does not guarantee proper second factor validation. This represents a significant regression in security posture that directly violates the principle of defense in depth as outlined in cybersecurity frameworks such as NIST SP 800-53.
The technical implementation flaw appears to stem from improper session management or authentication state validation within Nextcloud's authentication subsystem. When users provide correct username and password combinations, the system should enforce mandatory second factor verification before granting full access to the user account. However, under specific conditions, the authentication process fails to properly validate the second factor, allowing unauthorized access to user resources. This type of vulnerability aligns with CWE-305 authentication bypass weaknesses and falls under the ATT&CK technique T1212 for exploitation of credential exposure. The flaw likely exists in the session handling logic where authentication tokens or session states are not properly validated against second factor requirements.
The operational impact of this vulnerability extends beyond simple unauthorized access to include potential data breaches, privilege escalation, and lateral movement within affected environments. Organizations relying on Nextcloud for personal cloud storage and collaboration services face significant risk when this vulnerability is exploited, particularly in environments where sensitive personal data, business information, or confidential communications are stored. The vulnerability is particularly concerning because it operates silently, without alerting administrators to the failed second factor enforcement, making it difficult to detect unauthorized access attempts. This type of authentication bypass can enable attackers to access not only user files but also potentially compromise other systems if Nextcloud is integrated with enterprise identity management solutions or if users have elevated privileges within the organization.
Organizations must immediately implement the recommended security updates to address this vulnerability, with specific versions provided for both Nextcloud Community and Enterprise editions. The patch releases 26.0.13, 27.1.8, and 28.0.4 for Nextcloud Community Server, along with their corresponding Enterprise versions, contain the necessary fixes to properly enforce second factor authentication requirements. Security teams should conduct immediate vulnerability assessments to identify systems running vulnerable versions and ensure proper patch management procedures are in place. Additionally, organizations should review their authentication logs for any suspicious activities that might indicate exploitation attempts and implement enhanced monitoring for authentication events. The remediation process should include thorough testing of the updated systems to ensure that second factor authentication is properly enforced and that legitimate users can continue to access their accounts without disruption. This vulnerability demonstrates the critical importance of maintaining up-to-date security patches and proper authentication controls in cloud-based collaboration platforms.