CVE-2023-3907 in Enterprise Edition
Summary
by MITRE • 12/18/2023
A privilege escalation vulnerability in GitLab EE affecting all versions from 16.0 prior to 16.4.4, 16.5 prior to 16.5.4, and 16.6 prior to 16.6.2 allows a project Maintainer to use a Project Access Token to escalate their role to Owner
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Analysis
by VulDB Data Team • 10/03/2024
This privilege escalation vulnerability in GitLab Enterprise Edition represents a critical access control flaw that undermines the principle of least privilege within the platform's permission model. The vulnerability affects multiple version streams including 16.0 through 16.3.x, 16.5 through 16.5.3, and 16.6 through 16.6.1, creating a widespread impact across the GitLab ecosystem. The flaw specifically enables project maintainers to leverage project access tokens as a means to elevate their privileges to owner level, bypassing the intended security boundaries that should separate these roles.
The technical implementation of this vulnerability stems from insufficient validation of access token permissions within the project access token creation and usage workflow. When a project maintainer generates a project access token, the system fails to properly enforce the restriction that such tokens should only grant the permissions of the token creator's role. This design flaw allows the maintainer to subsequently use the access token to perform operations that should be restricted to project owners only, effectively creating a path for privilege escalation through legitimate system functionality.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on GitLab's role-based access control system. Project maintainers who might have legitimate but restricted access to certain repositories can exploit this flaw to gain full administrative control over projects, potentially leading to unauthorized code changes, access to sensitive data, and the ability to modify project configurations. The vulnerability is particularly concerning because it leverages existing legitimate functionality rather than requiring exploitation of additional system weaknesses, making it more difficult to detect and prevent.
The vulnerability aligns with CWE-276, which addresses improper privileges, and represents a classic case of insufficient access control validation within a system that should enforce strict role boundaries. From an adversary perspective, this vulnerability maps to ATT&CK technique T1078.004, which covers valid accounts with elevated privileges, as it allows attackers to escalate from a maintainer role to an owner role using legitimate access tokens. Organizations should immediately implement mitigation strategies including updating to the patched versions, reviewing existing project access tokens, and monitoring for suspicious access patterns that might indicate exploitation attempts.
The security implications extend beyond simple privilege escalation as this vulnerability could enable attackers to bypass other security controls that are typically enforced at the owner level. Project owners have capabilities such as managing project members, configuring webhooks, and modifying project settings that are not available to maintainers, making the escalation particularly dangerous. Additionally, the vulnerability demonstrates the importance of proper token validation and the potential for legitimate system features to be exploited when access controls are not properly enforced, highlighting the need for comprehensive security testing of access control mechanisms.