The flaw allows an authenticated user to run arbitrary system commands on the host by embedding shell metacharacters into a backup filename. During upload the BackupManager stores the file using the original name without sanitization. When a restore request later references that file, the host interprets the special characters and executes them, giving the attacker control over the server.

This vulnerability affects runtipi runtipi versions 3.7.0 and newer. The issue was fixed in release 4.7.0, which includes proper validation of backup filenames before storage and restoration.

The severity is high with a CVSS score of 8.1, but the current EPSS score is below 1% indicating a very low probability of exploitation in the wild. The vulnerability does not yet appear in the CISA KEV catalog. Exploitation requires the attacker to have authenticated access to the application and to trigger a backup upload followed by a restore operation. The attack vector is therefore likely a trusted environment or an internal network where legitimate users or compromised accounts can interact with the backup feature.