My Cloud OS 5 was vulnerable to a pre-authenticated stack overflow vulnerability on the FTP service that could be exploited by unauthenticated attackers on the network. Addressed the vulnerability by adding defenses against stack overflow issues.

Western Digital My Cloud OS 5 devices before 5.10.122 mishandle Symbolic Link Following on SMB and AFP shares. This can lead to code execution and information disclosure (by reading local files).

An issue was discovered on Western Digital MyCloud PR4100 2.30.172 devices. The web administration component, /web/jquery/uploader/multiuploadify.php, provides multipart upload functionality that is accessible without authentication and can be used to place a file anywhere on the device's file system. This allows an attacker the ability to upload a PHP shell onto the device and obtain arbitrary code execution as root.