What is CVE-2020-27158?

CVE-2020-27158 is a critical-severity vulnerability in Westerndigital My Cloud Ex4100, classified under OS Command Injection. CVSS score: 9.8/10. Published 2020-10-27.

How severe is CVE-2020-27158?

Critical severity. CVSS v3 base score is 9.8 out of 10.

RCE in Westerndigital My Cloud Ex4100

CVE-2020-27158

Addressed remote code execution vulnerability in cgi_api.php that allowed escalation of privileges in Western Digital My Cloud NAS devices prior to 5.04.114.

Vulnerability class: Command Injection (OS Command Injection)

Published 2020-10-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.075 (94.3th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 94th percentile — 94.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.075 · newest: 0.075 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-78 — OS Command Injection

References

www.westerndigital.com/support/productsecurity (Vendor Advisory)
www.westerndigital.com/support/productsecurity/wdc-20007-my-cloud-firmware-vers… (Vendor Advisory)
www.comparitech.com/blog/information-security/security-vulnerabilities-80000-de… (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2020-27158?: CVE-2020-27158 is a critical-severity vulnerability in Westerndigital My Cloud Ex4100, classified under OS Command Injection. CVSS score: 9.8/10. Published 2020-10-27.
How severe is CVE-2020-27158?: Critical severity. CVSS v3 base score is 9.8 out of 10.