CVE-2023-6477 is a security vulnerability identified in GitLab Enterprise Edition (EE) versions starting from 16.5 up to but not including 16.7.6, versions from 16.8 up to but not including 16.8.3, and versions from 16.9 up to but not including 16.9.1. The vulnerability stems from incorrect privilege assignment related to custom roles that include the admin_group_member permission. Specifically, a user assigned such a custom role may exploit this flaw to escalate their privileges by making themselves, other members, or even the group itself Owners of a group. This escalation can lead to unauthorized administrative control over group resources within GitLab. The underlying weakness is classified under CWE-266, which pertains to improper privilege management. The vulnerability has a CVSS v3.1 base score of 6.7, indicating a medium severity level. The vector string (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L) shows that the attack can be performed remotely over the network with low attack complexity, requires high privileges but no user interaction, and impacts confidentiality and integrity significantly, with a low impact on availability. No known exploits are currently reported in the wild, and no official patches are linked in the provided data, though it is implied that fixed versions exist beyond the affected ranges. This vulnerability is critical in environments where GitLab is used for source code management and collaboration, as unauthorized privilege escalation could lead to code tampering, data leakage, or disruption of development workflows.

For European organizations, this vulnerability poses a significant risk especially for those relying heavily on GitLab EE for software development and collaboration. Unauthorized privilege escalation to group Owner level can allow attackers or malicious insiders to modify repository settings, alter code, inject malicious code, or exfiltrate sensitive intellectual property. This can compromise the integrity and confidentiality of software projects, potentially affecting product security and compliance with regulations such as GDPR if personal data is involved. The medium severity score reflects the need for prompt remediation, particularly in sectors with high-value intellectual property or critical infrastructure software development. The risk is heightened in organizations with complex group structures and custom role assignments, where privilege boundaries may already be nuanced. Additionally, the vulnerability could be leveraged in supply chain attacks, impacting downstream users and partners across Europe. Given the remote network attack vector and lack of required user interaction, exploitation could be automated or performed stealthily by insiders with elevated privileges.

European organizations should immediately audit their GitLab EE installations to identify if they are running affected versions (16.5 up to 16.7.6, 16.8 up to 16.8.3, or 16.9 up to 16.9.1). They should prioritize upgrading to the fixed versions beyond these ranges as soon as official patches are available from GitLab. Until patches are applied, organizations should review and restrict the assignment of custom roles containing the admin_group_member permission, limiting it to only the most trusted administrators. Implement strict role-based access control (RBAC) policies and monitor group ownership changes through GitLab audit logs to detect suspicious privilege escalations. Employ network segmentation and multi-factor authentication (MFA) for GitLab access to reduce the risk of compromised credentials being used for exploitation. Additionally, consider deploying runtime monitoring tools that can alert on anomalous permission changes or unusual administrative activities within GitLab. Regularly review and update incident response plans to include scenarios involving privilege escalation within development platforms.