Dalfox, an open-source XSS scanner, contains a critical command injection vulnerability in versions prior to 2.13.0. When running in REST API server mode, the application binds to 0.0.0.0:6664 without requiring authentication by default. Attackers can exploit this by sending malicious JSON payloads to the POST /scan endpoint, which deserializes user input including FoundAction and FoundActionShell fields. These fields are passed directly to the scan options without sanitization, allowing unauthenticated remote attackers to execute arbitrary shell commands on the host system whenever a scan finding is triggered. The vulnerability affects the default configuration and has been patched in version 2.13.0.