CVE-2018-19856 in Community Edition
Summary
by MITRE
GitLab CE/EE before 11.3.12, 11.4.x before 11.4.10, and 11.5.x before 11.5.3 allows Directory Traversal in Templates API.
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Analysis
by VulDB Data Team • 08/08/2023
The vulnerability identified as CVE-2018-19856 represents a critical directory traversal flaw affecting GitLab Community Edition and Enterprise Edition versions prior to specific patch releases. This security weakness resides within the Templates API component of the GitLab platform, which is commonly used for creating and managing project templates across various development environments. The vulnerability stems from insufficient input validation and path sanitization mechanisms that fail to properly restrict user-supplied data when processing template requests. Attackers can exploit this flaw by crafting malicious requests that manipulate file paths to access unauthorized directories on the server filesystem. The issue manifests when the application processes template parameters without adequate sanitization, allowing attackers to traverse directory structures beyond the intended scope.
The technical exploitation of this vulnerability occurs through crafted API requests that manipulate template path parameters to navigate the file system hierarchy. When GitLab processes these requests, the lack of proper path validation enables attackers to access files outside of the designated template directories. This allows unauthorized access to sensitive system files, configuration data, and potentially other users' project files. The vulnerability is classified under CWE-22 as "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" which is a well-documented weakness in software applications that handle file operations. The attack vector specifically targets the API endpoints responsible for template management, where the application fails to validate or sanitize the template path parameters before processing them.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially lead to complete system compromise. An attacker who successfully exploits this directory traversal vulnerability could access sensitive configuration files, database credentials, and other system resources that are typically protected from normal user access. The exposure of such information could enable further attacks including privilege escalation, data exfiltration, and persistent access to the compromised GitLab instance. Additionally, the vulnerability affects multiple version streams of GitLab, indicating a widespread issue that required coordinated patching efforts across different release branches. Organizations running affected versions face significant risk as this flaw could be exploited by both internal and external threat actors without requiring elevated privileges.
Organizations should immediately upgrade to the patched versions of GitLab including 11.3.12, 11.4.10, and 11.5.3 to remediate this vulnerability. The patch implementation addresses the root cause by introducing proper input validation and path sanitization measures within the Templates API component. Security teams should also implement network-level controls and monitor API access logs for suspicious activity that might indicate exploitation attempts. The mitigation strategy should include validating all user inputs, implementing proper access controls, and conducting regular security assessments of API endpoints. This vulnerability aligns with ATT&CK technique T1083 "File and Directory Discovery" as attackers may attempt to enumerate system files after initial access. Organizations should also consider implementing web application firewalls and API gateways to provide additional layers of protection against similar path traversal attacks. The incident underscores the importance of maintaining up-to-date software versions and implementing robust input validation practices across all application components that handle file system operations.