CVE-2023-5933 in Community Edition
Summary
by MITRE • 01/26/2024
An issue has been discovered in GitLab CE/EE affecting all versions after 13.7 before 16.6.6, 16.7 prior to 16.7.4, and 16.8 prior to 16.8.1. Improper input sanitization of user name allows arbitrary API PUT requests.
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Analysis
by VulDB Data Team • 11/20/2025
The vulnerability identified as CVE-2023-5933 represents a critical security flaw in GitLab Community Edition and Enterprise Edition platforms that impacts versions ranging from 13.7 through 16.6.5, 16.7 through 16.7.3, and 16.8 through 16.8.0. This issue stems from inadequate input sanitization mechanisms within the user name validation process, creating a pathway for malicious actors to exploit the system through crafted API requests. The vulnerability specifically targets the application's handling of user-provided data during API PUT operations, where insufficient validation allows attackers to inject malformed or malicious input that bypasses normal security controls.
The technical root cause of this vulnerability lies in the improper sanitization of user name parameters within GitLab's API endpoints. When users submit data through API PUT requests, the system fails to adequately validate or sanitize the user name field, allowing special characters, escape sequences, or malformed data to propagate through the system without proper filtering. This weakness enables attackers to manipulate the API behavior by crafting requests that appear legitimate but contain hidden malicious payloads. The flaw operates at the input validation layer, where the system should have implemented robust sanitization measures to prevent potentially harmful data from being processed.
From an operational perspective, this vulnerability presents significant risks to GitLab installations as it allows attackers to perform unauthorized API operations that could lead to data manipulation, privilege escalation, or system compromise. The impact extends beyond simple data corruption, as the ability to craft arbitrary PUT requests means attackers could potentially modify user accounts, alter repository settings, or manipulate system configurations. The vulnerability affects the core authentication and authorization mechanisms within GitLab, potentially enabling attackers to gain elevated privileges or execute unauthorized actions that should normally be restricted to authorized users only. Security researchers have identified that this flaw could be exploited in conjunction with other vulnerabilities to create more severe attack vectors.
The security implications of CVE-2023-5933 align with CWE-20, which describes "Improper Input Validation" as a fundamental weakness in software systems. This classification indicates that the vulnerability represents a basic security flaw in how the application processes user input, making it a critical concern for organizations that rely on GitLab for version control and collaboration. The ATT&CK framework categorizes this type of vulnerability under T1078, which deals with Valid Accounts, as attackers could potentially leverage this weakness to manipulate user accounts or gain unauthorized access to system resources. Organizations should consider this vulnerability as part of a broader attack surface that could enable lateral movement within their infrastructure if not properly addressed.
Mitigation strategies for CVE-2023-5933 require immediate implementation of updated GitLab versions that contain the necessary patches and fixes. System administrators should prioritize upgrading to versions 16.6.6, 16.7.4, or 16.8.1, which contain the specific fixes for this input sanitization issue. Additionally, organizations should implement network-level monitoring to detect unusual API activity patterns that might indicate exploitation attempts. The implementation of proper input validation controls at the application layer, including regular expression filtering for user name fields, should be enforced. Organizations should also consider implementing API rate limiting and request validation mechanisms to prevent abuse of the affected endpoints. Security teams should conduct comprehensive vulnerability assessments to identify any potential exploitation attempts and ensure that all GitLab installations are properly updated to prevent unauthorized access to sensitive repository data and system configurations.