Link following in Western Digital products - CVE-2021-3310

Vulnerability identifier: #VU51481

CSH Severity: High

CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2021-3310

CWE-ID: CWE-59

Exploitation vector: Remote access

Exploit availability: Public exploit is available

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to the affected software mishandle Symbolic Link Following within the SMB and AFP services. A remote attacker can create a symlink to read arbitrary files and gain access to sensitive information or execute arbitrary code on the system.

My Cloud EX2 Ultra
My Cloud Mirror Gen 2
My Cloud EX4100
My Cloud PR2100
My Cloud PR4100
My Cloud DL2100
My Cloud DL4100
My Cloud EX2100
My Cloud (P/N: WDBCTLxxxxxx-10)

Install updates from vendor's website.

My Cloud EX2 Ultra - update to 5.10.122
My Cloud Mirror Gen 2 - update to 5.10.122
My Cloud EX4100 - update to 5.10.122
My Cloud PR2100 - update to 5.10.122
My Cloud PR4100 - update to 5.10.122
My Cloud DL2100 - update to 5.10.122
My Cloud DL4100 - update to 5.10.122
My Cloud EX2100 - update to 5.10.122
My Cloud (P/N: WDBCTLxxxxxx-10) - update to 5.10.122

• Exploit #5485 - CVE-2021-3310 (Western Digital MyCloud PR4100 Link Resolution Information Disclosure Vulnerability) (May 25, 2021)

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

• Link following in Western Digital My Cloud devices