CVE-2020-13286: 
GitLab vulnerability analysis and mitigation

A Server-Side Request Forgery (SSRF) vulnerability was discovered in GitLab versions 12.7 through 13.2.2, identified as CVE-2020-13286. The vulnerability was related to user-controlled git configuration settings when importing repositories via URL. This security issue was discovered and responsibly reported by security researcher @vakzz (GitLab Release).

The vulnerability existed in GitLab's repository import functionality where the git http configuration settings could be manipulated through the import URL. When importing a repository with credentials via URL, GitLab's Gitaly component would generate a git clone command with a -c flag to add the Authorization header. However, the URL could contain HTTP config values from git-config documentation, allowing an attacker to set configurations like http.proxy instead of the intended extraHeader setting (GitLab Issue).

The vulnerability allowed attackers to perform Server-Side Request Forgery (SSRF) attacks by manipulating the git configuration settings. This could potentially enable attackers to send unauthorized requests to internal services or external systems using GitLab's server as a proxy (GitLab Issue).

The vulnerability could be exploited by creating a project with a specially crafted import URL that manipulated git configuration settings. The attacker could set values like http.proxy, which would allow them to route requests through arbitrary proxy servers, potentially accessing internal resources or performing SSRF attacks (GitLab Issue).

The vulnerability was patched in GitLab versions 13.2.3, 13.1.6, and 13.0.12. Users running affected versions were strongly recommended to upgrade to these patched versions immediately to address the security issue (GitLab Release).