What is CVE-2021-27663?

CVE-2021-27663 is a high-severity vulnerability in Johnson Controls Cem Systems Ac2000, classified under Improper Authorization. CVSS score: 8.2/10. Published 2021-08-30.

How severe is CVE-2021-27663?

High severity. CVSS v3 base score is 8.2 out of 10.

Auth bypass in Johnson Controls Cem Systems Ac2000

CVE-2021-27663

A vulnerability in versions 10.1 through 10.5 of Johnson Controls CEM Systems AC2000 allows a remote attacker to access to the system without adequate authorization. This issue affects: Johnson Controls CEM Systems AC2000 10.1; 10.2; 10.3; 10.4; 10.5.

Published 2021-08-30 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.017 (75.8th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 76th percentile — 75.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: 0.000

Affected products

Johnson Controls Cem Systems Ac2000 — versions 10.1
Johnsoncontrols Ac2000
Johnsoncontrols Ac2000 Firmware

Weakness classification (CWE)

CWE-285 — Improper Authorization

References

www.johnsoncontrols.com/cyber-solutions/security-advisories (Vendor Advisory)
us-cert.gov/ics/advisories/ICSA-21-238-01 (US Government Resource, Third Party Advisory, third-party-advisory)

Frequently asked questions

What is CVE-2021-27663?: CVE-2021-27663 is a high-severity vulnerability in Johnson Controls Cem Systems Ac2000, classified under Improper Authorization. CVSS score: 8.2/10. Published 2021-08-30.
How severe is CVE-2021-27663?: High severity. CVSS v3 base score is 8.2 out of 10.