ConvertX is a self-hosted file conversion service. Prior to 0.18.0, the ImageMagick converter uses the unsanitized convert_to parameter to construct an output path. If an authenticated user, or an unauthenticated user when ConvertX is configured to allow unauthenticated access, uploads an extensionless image and supplies directory traversal sequences in convert_to through /convert, the constructed path escapes the intended output directory, allowing the attacker to write converted output to arbitrary container paths, potentially overwriting files or causing denial of service. This issue is fixed in version 0.18.0.