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).
https://www.zerodayinitiative.com/advisories/ZDI-21-277/
https://www.westerndigital.com/support/productsecurity/wdc-21002-my-cloud-firmware-version-5-10-122