What is CVE-2021-20850?

CVE-2021-20850 is a critical-severity vulnerability in Alfasado Powercms, classified under OS Command Injection. CVSS score: 9.8/10. Published 2021-11-24.

How severe is CVE-2021-20850?

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

RCE in Alfasado Powercms

CVE-2021-20850

PowerCMS XMLRPC API of PowerCMS 5.19 and earlier, PowerCMS 4.49 and earlier, PowerCMS 3.295 and earlier, and PowerCMS 2 Series (End-of-Life, EOL) allows a remote attacker to execute an arbitrary OS command via unspecified vectors.

Vulnerability class: Command Injection (OS Command Injection)

Published 2021-11-24 · 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: 0.015 (73.8th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 74th percentile — 73.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.015 · newest: 0.015 · change: +0.000

Affected products

Alfasado Powercms
Alfasado Inc. Powercms Xmlrpc API — versions PowerCMS 5.19 and earlier, PowerCMS 4.49 and earlier, PowerCMS 3.295 and earlier, PowerCMS 2 Series (End-of-Life, EOL)

Weakness classification (CWE)

CWE-78 — OS Command Injection

References

www.powercms.jp/news/release-patch-xmlrpc-api-202110.html (Patch, Vendor Advisory)
jvn.jp/en/jp/JVN17645965/index.html (Third Party Advisory)

Frequently asked questions

What is CVE-2021-20850?: CVE-2021-20850 is a critical-severity vulnerability in Alfasado Powercms, classified under OS Command Injection. CVSS score: 9.8/10. Published 2021-11-24.
How severe is CVE-2021-20850?: Critical severity. CVSS v3 base score is 9.8 out of 10.