CVE-2024-56731

### Summary Due to the insufficient patch for the CVE-2024-39931, it's still possible to delete files under the `.git` directory and achieve remote command execution. ### Details In the patch for CVE-2024-39931, the following check is added: https://github.com/gogs/gogs/commit/77a4a945ae9a87f77e392e9066b560edb71b5de9 ```diff + // 🚨 SECURITY: Prevent uploading files into the ".git" directory + if isRepositoryGitPath(opts.TreePath) { + return errors.Errorf("bad tree path %q", opts.TreePath) + } ``` While the above code snippet checks if the specified path is a `.git` directory, there are no checks for symbolic links in the later steps. So, by creating a symbolic link that points to the `.git` directory, an attacker can still delete arbitrary files in the `.git` directory and achieve remote command execution. ### Impact Unprivileged user accounts can execute arbitrary commands on the Gogs instance with the privileges of the account specified by `RUN_USER` in the configuration. It allows attackers to access and alter any users' code hosted on the same instance.