CVE-2023-31485 in GitLab::API::v4
Summary
by MITRE • 04/29/2023
GitLab::API::v4 through 0.26 does not verify TLS certificates when connecting to a GitLab server, enabling machine-in-the-middle attacks.
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Analysis
by VulDB Data Team • 12/26/2025
The vulnerability identified as CVE-2023-31485 affects GitLab::API::v4 versions through 0.26 and represents a critical security flaw in the client-side implementation of GitLab's API integration. This issue stems from the absence of proper Transport Layer Security certificate verification during communication with GitLab servers, creating a significant attack surface that adversaries can exploit to compromise the integrity of the communication channel. The flaw directly impacts the cryptographic security posture of systems relying on this API client library, as it fails to validate the authenticity of server certificates presented during TLS handshakes.
The technical implementation of this vulnerability resides in the API client's network communication stack where certificate validation routines are either absent or improperly configured. When the GitLab::API::v4 client attempts to establish secure connections to GitLab servers, it does not perform certificate chain validation, hostname verification, or certificate trust verification processes that are fundamental to TLS security protocols. This omission allows attackers to intercept and manipulate communications between the client and server by presenting fraudulent certificates that would normally be rejected by proper certificate validation mechanisms. The vulnerability operates at the application layer where the client library handles HTTPS connections without enforcing the standard certificate verification procedures that should occur during TLS negotiation.
The operational impact of this vulnerability extends beyond simple data interception to enable sophisticated man-in-the-middle attacks that can compromise the confidentiality and integrity of all communications between the client application and GitLab servers. Attackers can leverage this weakness to gain access to sensitive data including API tokens, repository contents, user credentials, and other confidential information transmitted through the compromised communication channel. The vulnerability affects any system utilizing GitLab::API::v4 version 0.26 or earlier in applications that require secure communication with GitLab instances, potentially exposing development environments, CI/CD pipelines, and automated deployment systems to unauthorized access and data manipulation.
Organizations should immediately update their GitLab::API::v4 client libraries to versions that properly implement TLS certificate verification and certificate pinning where appropriate. The mitigation strategy involves ensuring that all client applications perform proper certificate validation, including hostname checking, certificate chain validation, and trust verification against established certificate authorities. Security teams should also implement network monitoring to detect anomalous certificate behavior and consider implementing certificate transparency monitoring to identify potential certificate misconfigurations. This vulnerability aligns with CWE-295 which addresses improper certificate validation and relates to ATT&CK technique T1573.002 for Lateral Movement through secure channel manipulation, highlighting the critical nature of proper certificate validation in maintaining secure communications within development and operational environments.
The broader implications of this vulnerability demonstrate the importance of secure coding practices and the necessity of implementing comprehensive security controls even in seemingly simple client libraries. Development teams should prioritize security considerations during library integration and ensure that all network communication components properly validate certificates and enforce secure connection protocols. Organizations relying on GitLab API integrations must conduct thorough security assessments of their client implementations and establish monitoring procedures to detect potential certificate validation failures that could indicate active exploitation attempts.