CVE-2023-1265: 
GitLab vulnerability analysis and mitigation

An issue was discovered in GitLab that allows a privileged attacker with Grafana admin access to obtain session tokens from all users of a GitLab instance. The vulnerability (CVE-2023-1265) was discovered on February 27, 2023, and publicly disclosed on May 3, 2023. This vulnerability affects GitLab instances with integrated Grafana servers running under the same domain (GitLab Issue).

The vulnerability exists due to GitLab's integrated Grafana server running under the same origin as the GitLab instance (e.g., https://gitlab.example.com/-/grafana). When configuring a data source in Grafana, administrators can whitelist cookies that will be forwarded from the user's request to the data source. Since both servers share the same domain, the GitLab session cookie (_gitlab_session) is accessible to Grafana and can be forwarded to an attacker-controlled server through a malicious data source configuration (GitLab Issue). The vulnerability has been assigned a CVSS v3.1 score of 5.4 (Medium) (NVD).

The exploitation of this vulnerability can lead to session token theft, allowing attackers to perform complete account takeover of any user who visits a dashboard containing the malicious data source. The impact is particularly severe if an administrator's session is compromised, as it could result in full administrative access to the GitLab instance (GitLab Issue).

GitLab has addressed this vulnerability through security updates. Organizations running GitLab instances should ensure they are updated to a patched version. Additionally, organizations should carefully consider the necessity of granting Grafana admin access and potentially host Grafana on a separate subdomain to prevent cookie sharing (GitLab Issue).