CVE-2016-9086 in GitLab
Summary
by MITRE
GitLab versions 8.9.x and above contain a critical security flaw in the "import/export project" feature of GitLab. Added in GitLab 8.9, this feature allows a user to export and then re-import their projects as tape archive files (tar). All GitLab versions prior to 8.13.0 restricted this feature to administrators only. Starting with version 8.13.0 this feature was made available to all users. This feature did not properly check for symbolic links in user-provided archives and therefore it was possible for an authenticated user to retrieve the contents of any file accessible to the GitLab service account. This included sensitive files such as those that contain secret tokens used by the GitLab service to authenticate users. GitLab CE and EE versions 8.13.0 through 8.13.2, 8.12.0 through 8.12.7, 8.11.0 through 8.11.10, 8.10.0 through 8.10.12, and 8.9.0 through 8.9.11 are affected.
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Analysis
by VulDB Data Team • 05/26/2019
The vulnerability described in CVE-2016-9086 represents a critical access control flaw within GitLab's import/export project functionality that emerged in version 8.9.0 and persisted through multiple release lines until the 8.13.3 patch was issued. This security weakness specifically targeted the tar archive handling mechanism used during project import operations, creating a path for authenticated users to bypass normal file system access restrictions. The flaw was introduced when GitLab 8.13.0 expanded the import/export feature from administrator-only access to all users, inadvertently creating a security gap that allowed arbitrary file read access through maliciously crafted archive contents.
The technical exploitation of this vulnerability relies on the improper handling of symbolic links within user-provided tar archives during the import process. When GitLab processes an imported project archive, it does not adequately validate or sanitize symbolic links that may point to sensitive system files accessible to the GitLab service account. This design flaw falls under the Common Weakness Enumeration category of improper input validation and weak file system access controls, specifically CWE-22 for path traversal and CWE-73 for improper neutralization of special elements. The vulnerability enables an authenticated attacker to craft a tar archive containing symbolic links that point to critical system files such as configuration files containing secret tokens, database credentials, or other sensitive information that the GitLab service account can access.
The operational impact of this vulnerability is severe and far-reaching for organizations using affected GitLab versions. An authenticated user, even with limited privileges, could extract sensitive information from the GitLab server including API tokens, database connection strings, SSH keys, and other confidential data that would normally be restricted to system administrators. This represents a privilege escalation attack vector where a regular user can effectively gain access to system-level information that should only be available to privileged accounts. The vulnerability directly impacts the confidentiality and integrity of the GitLab instance, potentially enabling further attacks such as lateral movement within the network or credential theft that could compromise the entire development infrastructure.
Organizations using affected GitLab versions should immediately implement mitigations including upgrading to patched versions 8.13.3 or later, which contain proper validation of symbolic links during archive extraction. System administrators should also consider implementing additional controls such as restricting import/export functionality to trusted administrators only, monitoring for unusual import activities, and conducting thorough security audits of the GitLab service account permissions. The ATT&CK framework categorizes this vulnerability under T1078 for valid accounts and T1566 for malicious file execution, highlighting the importance of proper access controls and the potential for this vulnerability to serve as a foothold for more sophisticated attacks. Organizations should also review their network segmentation and access controls to minimize the potential impact of credential exposure resulting from this vulnerability.