CVE-2023-0989 is a medium-severity information disclosure vulnerability affecting GitLab Community Edition (CE) and Enterprise Edition (EE) versions starting from 13.11 up to versions prior to 16.2.8, 16.3 prior to 16.3.5, and 16.4 prior to 16.4.1. The vulnerability arises from improper ownership management (CWE-282) in GitLab's handling of CI/CD variables. Specifically, an attacker can craft a malicious fork of a repository containing a specially designed CI/CD configuration. When a legitimate user visits this fork, the malicious configuration can trick GitLab into exposing non-protected CI/CD variables that should normally remain confidential. These variables often contain sensitive information such as API keys, tokens, or credentials used in automated build and deployment pipelines. The vulnerability does not require user interaction beyond visiting the malicious fork and does not require elevated privileges beyond those of a standard user with access to the repository. The CVSS 3.1 base score is 4.3, reflecting a network attack vector with low complexity, requiring low privileges but no user interaction, and resulting in limited confidentiality impact without affecting integrity or availability. No known exploits in the wild have been reported to date. The vulnerability underscores the risk of trusting forked repositories and the need for strict controls around CI/CD variable exposure in collaborative development environments.

For European organizations using GitLab for source code management and CI/CD pipelines, this vulnerability could lead to unauthorized disclosure of sensitive CI/CD variables. Such exposure can compromise credentials used for deployment, cloud services, or third-party integrations, potentially enabling further attacks such as unauthorized access to infrastructure, data exfiltration, or supply chain compromise. Organizations in sectors with stringent data protection requirements (e.g., finance, healthcare, critical infrastructure) may face regulatory and reputational risks if sensitive information is leaked. The vulnerability's exploitation does not directly affect system integrity or availability but can serve as a stepping stone for more severe attacks. Given the widespread adoption of GitLab across European enterprises and public sector entities, the risk is significant, especially if internal policies do not restrict access to forks or do not enforce strict variable protection mechanisms.

1. Upgrade GitLab instances to the fixed versions: 16.2.8, 16.3.5, or 16.4.1 or later as soon as possible to eliminate the vulnerability. 2. Review and audit all CI/CD variables, ensuring that sensitive variables are marked as protected and masked, and restrict their exposure only to trusted branches and pipelines. 3. Implement strict access controls on forked repositories and consider disabling or limiting pipeline execution on forks, especially from untrusted contributors. 4. Educate developers and users to avoid visiting or interacting with untrusted forks or repositories that could contain malicious CI/CD configurations. 5. Monitor CI/CD pipeline logs and variable usage for unusual activity that could indicate exploitation attempts. 6. Use GitLab’s security features such as push rules, merge request approvals, and pipeline security policies to reduce risk exposure. 7. Regularly review GitLab security advisories and apply patches promptly to maintain a secure environment.