CVE-2019-6790 in Community Edition
Summary
by MITRE
An Incorrect Access Control (issue 2 of 3) issue was discovered in GitLab Community and Enterprise Edition 8.14 and later but before 11.5.8, 11.6.x before 11.6.6, and 11.7.x before 11.7.1. Guest users were able to view the list of a group's merge requests.
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Analysis
by VulDB Data Team • 09/23/2023
The vulnerability described in CVE-2019-6790 represents a critical access control flaw in GitLab's permission model that affected multiple versions of the popular DevOps platform. This issue falls under the CWE-284 category of Improper Access Control, where the system failed to properly enforce authorization checks for specific user roles. The flaw specifically impacted GitLab Community and Enterprise Edition installations running versions from 8.14 through 11.5.7, as well as certain 11.6.x and 11.7.x releases prior to their respective security patches. The vulnerability allowed guest users to bypass normal access restrictions and gain visibility into merge request listings within groups they should not have been authorized to access.
The technical implementation of this flaw stemmed from inadequate validation of user permissions when processing requests for group merge request listings. In properly functioning systems, guest users should only have read access to specific project resources, but this vulnerability enabled them to enumerate all merge requests associated with a particular group. This access control bypass occurred at the application layer where the system failed to verify whether the requesting user possessed sufficient privileges to view merge request information. The flaw was particularly concerning because merge requests often contain sensitive information about code changes, proposed modifications, and development activities that may not be intended for public or guest viewing.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with valuable reconnaissance data about project development activities and team collaboration patterns. Guest users could potentially identify ongoing development work, understand team structures, and discover sensitive implementation details about the software being developed. This information could be leveraged by malicious actors to plan targeted attacks against specific projects or to gain intelligence about development practices and potential security weaknesses. The vulnerability also undermines the principle of least privilege that is fundamental to secure system design, as it allows users with minimal access rights to obtain information typically restricted to higher-privilege users.
Organizations running affected GitLab versions should immediately apply the available patches to mitigate this vulnerability, which were released as part of the 11.5.8, 11.6.6, and 11.7.1 updates. The fix implemented by GitLab developers involved strengthening access control checks for group merge request operations, ensuring that only users with appropriate permissions could view merge request listings. Security administrators should also conduct comprehensive audits of their GitLab installations to verify that no unauthorized access has occurred and consider implementing additional monitoring for unusual access patterns. This vulnerability aligns with ATT&CK technique T1068 which involves exploiting legitimate credentials and access rights to gain access to systems, though in this case the flaw was in the access control system itself rather than credential compromise. Organizations should also review their overall security posture and consider implementing additional access controls and monitoring to prevent similar issues in other applications and systems.