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The vulnerability arises from the PutContents API in Gogs, which handles file uploads or content writing operations. When processing user-supplied paths, the API fails to properly validate and restrict symbolic links (symlinks). An attacker with write permissions, such as a repository collaborator, can create a symbolic link pointing to a critical system file or directory outside the intended repository scope. By exploiting this, the attacker can trick the API into writing malicious content into sensitive locations, like configuration files or executable directories. This write primitive can be leveraged to inject code, such as web shells or scripts, into areas where it will be executed by the server or other processes. The improper handling occurs because the API follows symlinks without checking if the target is within the allowed directory tree. This allows traversal beyond the repository root. Consequently, by crafting a symlink that points to, for example, a web-accessible directory or a cron job folder, the attacker can achieve persistent remote code execution. The vulnerability is particularly dangerous in shared hosting environments or where Gogs is deployed with elevated privileges. The attack requires initial access to create a symlink, typically through the web interface or API calls. The flaw stems from insufficient path sanitization before file operations, a common issue in web applications that manage file systems.
Platform: Gogs
Version: Not specified
Vulnerability: Symbolic link mishandling
Severity: HIGH
date: Not provided
Prediction: Patch date unknown
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Create a symbolic link pointing to a sensitive location ln -s /etc/cron.daily/malicious_job /path/to/repository/link Use curl to trigger the PutContents API with the symlink curl -X POST -H "Authorization: token <token>" -d "content=malicious_payload" https://gogs-instance/api/v1/repos/owner/repo/contents/link
how Exploit:
Attacker creates symlink via repository.
Exploits PutContents API to write.
Writes payload to system location.
Triggers execution via cron/web.
Protection from this CVE
Update Gogs version.
Restrict file permissions.
Validate paths strictly.
Disable symlink following.
Impact:
Local code execution.
System compromise.
Data breach risk.
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Sources:
Reported By: www.cve.org
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