CVE-2019-15733 in Community Edition
Summary
by MITRE
An issue was discovered in GitLab Community and Enterprise Edition 7.12 through 12.2.1. The specified default branch name could be exposed to unauthorized users.
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Analysis
by VulDB Data Team • 12/25/2023
The vulnerability identified as CVE-2019-15733 represents a security flaw in GitLab Community and Enterprise Edition versions ranging from 7.12 through 12.2.1 where the default branch name of repositories could be exposed to unauthorized users. This issue falls under the category of information disclosure vulnerabilities and is classified as CWE-200, which specifically addresses the exposure of sensitive information to an unauthorized actor. The flaw exists in the application's handling of repository metadata and access control mechanisms, creating a scenario where users without proper authorization can gain knowledge about repository structures through the exposure of default branch names.
The technical implementation of this vulnerability stems from inadequate access controls within GitLab's repository management system. When users access repository information, the application fails to properly verify user permissions before exposing the default branch name. This exposure occurs even when users lack the appropriate access rights to view the repository contents or perform operations on the default branch. The vulnerability is particularly concerning because default branch names often contain significant information about repository purpose, development status, or project structure, providing attackers with valuable reconnaissance data for potential further attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can facilitate more sophisticated attack vectors within the software development lifecycle. Attackers can leverage the exposed default branch names to identify repositories with specific naming conventions that may indicate sensitive projects or development environments. This information can be used to target specific repositories for further reconnaissance, potentially leading to privilege escalation or access to sensitive code repositories. The vulnerability affects organizations using GitLab across multiple versions, creating a widespread impact across various deployment scenarios and potentially exposing numerous repositories to unauthorized information disclosure.
Organizations should implement immediate mitigations including upgrading to GitLab versions 12.3 or later where this vulnerability has been addressed through improved access control checks. System administrators should also review and audit existing access control policies to ensure proper repository permissions are enforced, particularly for default branch information. The vulnerability aligns with ATT&CK technique T1083, which covers the discovery of system information, and represents a clear violation of the principle of least privilege in information security. Additionally, organizations should consider implementing network-level monitoring to detect potential exploitation attempts and maintain comprehensive logging of repository access activities to identify unauthorized access patterns that may indicate exploitation of this vulnerability.