CVE-2019-20148 in Community Edition
Summary
by MITRE
An issue was discovered in GitLab Community Edition (CE) and Enterprise Edition (EE) 8.13 through 12.6.1. It has Incorrect Access Control.
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Analysis
by VulDB Data Team • 01/14/2020
This vulnerability exists within GitLab CE and EE versions ranging from 8.13 through 12.6.1, representing a critical access control flaw that allows unauthorized users to bypass intended security restrictions. The issue stems from improper validation of user permissions and access controls within the GitLab platform's authentication and authorization mechanisms. This weakness enables attackers to escalate privileges and gain unauthorized access to resources they should not be permitted to view or modify, fundamentally undermining the security posture of affected installations. The vulnerability specifically affects the platform's ability to properly enforce access restrictions for project members, administrators, and other user roles, creating potential pathways for privilege escalation and data exposure. Such flaws are particularly dangerous in collaborative development environments where GitLab serves as the central repository management system, as they can enable malicious actors to access sensitive code repositories, project configurations, and other confidential information.
The technical implementation of this access control flaw involves a failure in the permission validation logic that governs how GitLab handles user access requests. When users attempt to access specific resources or perform certain operations within the platform, the system does not properly verify whether the requesting user possesses the necessary permissions to perform those actions. This can occur through various vectors including direct API calls, web interface interactions, or programmatic access to project resources. The vulnerability manifests when the platform fails to correctly check user roles, group memberships, or project access levels during critical operations, allowing unauthorized access to protected resources. This issue is classified under CWE-284 which specifically addresses Improper Access Control, and aligns with ATT&CK technique T1078 which covers Valid Accounts and T1484 which covers Domain Controller Permissions. The flaw essentially creates a situation where users can bypass normal access controls through manipulated requests or by exploiting inconsistencies in the permission checking process.
The operational impact of this vulnerability extends far beyond simple unauthorized access, potentially enabling comprehensive system compromise and data breaches across affected GitLab installations. Organizations utilizing vulnerable GitLab versions face significant risks including unauthorized code modifications, exposure of sensitive intellectual property, potential for privilege escalation to administrative levels, and complete compromise of source code repositories. The vulnerability can be exploited by both internal and external attackers who gain access to any user account, as it allows them to escalate their privileges and access resources they should not be authorized to view. This includes accessing private projects, viewing confidential documentation, modifying code repositories, and potentially gaining administrative access to the entire GitLab instance. The scope of impact is particularly severe given that GitLab is widely used in enterprise environments, development teams, and organizations managing critical software projects where unauthorized access could result in significant financial, operational, and reputational damage. The vulnerability affects not only individual user accounts but also the integrity of entire project structures and access control policies.
Mitigation strategies for this vulnerability require immediate action including upgrading to GitLab versions 12.7.0 or later where the access control flaw has been patched. Organizations should implement comprehensive access control reviews to identify and remediate any unauthorized access that may have occurred during the vulnerability window. Network segmentation and monitoring should be enhanced to detect unusual access patterns or unauthorized attempts to escalate privileges within GitLab systems. Security teams should conduct thorough audits of user permissions, project access controls, and administrative privileges to ensure proper enforcement of access restrictions. Additionally, organizations should implement multi-factor authentication for administrative accounts and consider implementing additional monitoring controls to detect potential exploitation attempts. The patch addresses the core access control implementation by properly validating user permissions and ensuring that all access requests are properly authenticated against the correct permission sets. Organizations should also consider implementing automated security scanning tools to detect similar access control issues in their software environments and establish regular vulnerability assessment processes to identify and remediate security weaknesses before they can be exploited.