CVE-2024-0410 is a high-severity authorization bypass vulnerability in GitLab, a widely used web-based DevOps lifecycle tool that provides Git repository management, CI/CD pipelines, and code review features. The vulnerability affects GitLab versions 15.1 prior to 16.7.6, 16.8 prior to 16.8.3, and 16.9 prior to 16.9.1. It is classified under CWE-841, which relates to improper enforcement of behavioral workflow, specifically in the context of code review and approval processes. The flaw allows a developer with limited privileges (low-level privileges) to bypass the CODEOWNERS approval mechanism by intentionally creating a merge conflict. Normally, CODEOWNERS files enforce that specific users or teams must approve changes to certain parts of the codebase before merging. However, due to this vulnerability, an attacker can circumvent this control by exploiting the merge conflict handling logic, effectively merging code changes without the required approvals. The CVSS 3.1 base score is 7.7 (high), with the vector indicating network attack vector (AV:N), high attack complexity (AC:H), low privileges required (PR:L), user interaction required (UI:R), scope changed (S:C), and high impact on confidentiality and integrity (C:H/I:H), but no impact on availability (A:N). This means the vulnerability can be exploited remotely over the network but requires some user interaction and is somewhat complex to exploit. The scope change indicates that the vulnerability affects resources beyond the initially vulnerable component. Exploiting this flaw could allow unauthorized code changes to be merged into critical branches, potentially introducing malicious code, backdoors, or other security weaknesses into the software development lifecycle. No known exploits are currently reported in the wild, but the vulnerability is publicly disclosed and patched in later versions. Given GitLab's extensive use in software development environments, this vulnerability poses a significant risk to the integrity of codebases and the security of software supply chains.

For European organizations, this vulnerability poses a substantial risk to the integrity and trustworthiness of their software development processes. Many European enterprises, including financial institutions, government agencies, and technology companies, rely on GitLab for source code management and CI/CD pipelines. An attacker exploiting this vulnerability could bypass mandatory code review policies, leading to unauthorized code merges that may introduce malware, data exfiltration backdoors, or logic flaws. This undermines the confidentiality and integrity of the software supply chain, potentially resulting in compromised applications deployed in production environments. The impact is particularly critical for organizations subject to strict regulatory requirements such as GDPR, NIS Directive, and sector-specific cybersecurity mandates, where software integrity is paramount. Additionally, the vulnerability could facilitate insider threats or supply chain attacks, which have been increasingly targeted in Europe. The complexity of exploitation and requirement for user interaction somewhat limit mass exploitation but do not eliminate targeted attacks against high-value European organizations. The absence of known exploits in the wild currently provides a window for mitigation, but the public disclosure increases the risk of weaponization by threat actors.

European organizations should prioritize upgrading GitLab instances to the fixed versions: 16.7.6 or later for the 15.x branch, 16.8.3 or later for the 16.8 branch, and 16.9.1 or later for the 16.9 branch. Immediate patching is the most effective mitigation. Until patches are applied, organizations should enforce strict access controls limiting developer permissions to only those necessary, minimizing the number of users who can create merge requests. Implement additional manual code review checkpoints outside of GitLab’s automated CODEOWNERS enforcement to detect unauthorized merges or suspicious merge conflicts. Monitoring and alerting on unusual merge conflict patterns or merges bypassing approval workflows can help detect exploitation attempts. Integrating external code integrity verification tools or signing commits and merges can provide an additional layer of assurance. Organizations should also review and tighten their CI/CD pipeline security, ensuring that deployment processes verify code provenance and integrity before production rollout. Training developers and DevOps staff to recognize and report suspicious merge behaviors is recommended. Finally, maintaining an up-to-date inventory of GitLab versions deployed across the enterprise will aid in rapid response and patch management.