A device API endpoint was missing access controls on Western Digital My Cloud OS 5 iOS and Anroid Mobile Apps, My Cloud Home iOS and Android Mobile Apps, SanDisk ibi iOS and Android Mobile Apps, My Cloud OS 5 Web App, My Cloud Home Web App and the SanDisk ibi Web App. Due to a permissive CORS policy and missing authentication requirement for private IPs, a remote attacker on the same network as the device could obtain device information by convincing a victim user to visit an attacker-controlled server and issue a cross-site request.

This issue affects My Cloud OS 5 Mobile App: before 4.21.0; My Cloud Home Mobile App: before 4.21.0; ibi Mobile App: before 4.21.0; My Cloud OS 5 Web App: before 4.26.0-6126; My Cloud Home Web App: before 4.26.0-6126; ibi Web App: before 4.26.0-6126.

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 WD My Cloud v04.05.00-320 devices embed the session token (aka PHPSESSID) in filenames, which makes it easier for attackers to bypass authentication by listing a directory. NOTE: this can be exploited in conjunction with CVE-2018-7171 for remote authentication bypass within a product that uses My Cloud.