CVE-2021-39902 in Community Edition
Summary
by MITRE • 11/05/2021
Incorrect Authorization in GitLab CE/EE 13.4 or above allows a user with guest membership in a project to modify the severity of an incident.
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Analysis
by VulDB Data Team • 11/10/2021
The vulnerability identified as CVE-2021-39902 represents a critical authorization flaw within GitLab Community Edition and Enterprise Edition versions 13.4 and later. This issue affects the incident management functionality within GitLab, specifically targeting the authorization controls that govern who can modify incident severity levels. The flaw allows unauthorized users with guest-level permissions to manipulate incident severity settings, which directly undermines the security model and access controls implemented by the platform. This vulnerability exists within the core incident management system and represents a failure in the principle of least privilege enforcement.
The technical root cause of this vulnerability stems from inadequate authorization checks within the incident severity modification functionality. When a guest user attempts to modify an incident's severity level, the system fails to properly validate whether the user possesses the necessary permissions to perform such operations. This authorization bypass occurs at the application layer where the system should enforce strict access controls based on user roles and project membership levels. The flaw specifically impacts the incident management module and demonstrates a weakness in the permission model that governs administrative actions within project environments. According to CWE classification, this vulnerability maps to CWE-285: Improper Authorization, which encompasses issues where the system fails to properly enforce access controls for protected resources.
The operational impact of this vulnerability extends beyond simple privilege escalation as it allows guest users to potentially manipulate incident severity classifications that may affect incident response prioritization and resource allocation. An attacker with guest access could artificially reduce the severity of critical incidents, potentially delaying response times and undermining incident management processes. Conversely, they could also increase severity levels to create false alarms or disrupt normal operations. This vulnerability directly impacts the integrity of incident reporting and can compromise the effectiveness of security operations within organizations using GitLab. The flaw enables potential information disclosure through manipulation of incident data and can disrupt normal workflow processes. From an ATT&CK framework perspective, this vulnerability aligns with T1078: Valid Accounts and T1496: Resource Hijacking, as it allows for unauthorized modification of system resources and can be leveraged for operational disruption.
Organizations utilizing GitLab versions affected by CVE-2021-39902 should immediately implement mitigations including updating to patched versions of GitLab, reviewing and strengthening access controls, and monitoring for unauthorized incident modifications. The recommended solution involves applying the official security patches released by GitLab to address the authorization flaw. Additionally, administrators should conduct thorough access control reviews to ensure that only authorized personnel have the ability to modify incident severity levels. Network monitoring should be enhanced to detect unusual activity patterns related to incident management modifications. Organizations should also consider implementing additional security controls such as privileged access management solutions and regular security audits of access permissions. The vulnerability demonstrates the importance of maintaining up-to-date software versions and the critical need for robust authorization mechanisms in collaborative development environments where multiple user roles interact with sensitive operational data.