Multiple Western Digital MyCloud Networked Attached Storage (NAS) devices are affected by several security flaws, varying in severity, that allow attackers to bypass authentication, execute code on the device, and upload or download user data. The flaws have not been reported to Western Digital, are still unpatched, and with public exploit code is available for more than half of the vulnerabilities. The most severe of these issues is authentication bypass issue, which ironically was also the easiest to exploit, requiring only the modification of cookie session parameters.
Source: https://www.bleepingcomputer.com/news/security/multiple-unpatched-vulnerabilities-discovered-in-western-digital-nas-hard-drives/