How severe is CVE-2021-27663?

CVE-2021-27663 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.

Is CVE-2021-27663 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27663?

CVE-2021-27663 affects Johnsoncontrols Ac2000 Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27663?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-27663 published?

CVE-2021-27663 was published on 2021-08-30 and last updated on 2026-06-17.

CVE-2021-27663

CVE-2021-27663 is a high-severity vulnerability in Johnsoncontrols Ac2000 Firmware with a CVSS 3.x base score of 8.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-285.

Key facts

Severity: High (CVSS 3.x base score 8.2)
CVSS v2: 9.3
EPSS exploit prediction: 2% (74th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-285
Affected product: Johnsoncontrols Ac2000 Firmware
Published: 2021-08-30
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-27663?: CVE-2021-27663 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.
Is CVE-2021-27663 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27663?: CVE-2021-27663 affects Johnsoncontrols Ac2000 Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27663?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-27663 published?: CVE-2021-27663 was published on 2021-08-30 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:johnsoncontrols:ac2000_firmware:*:*:*:*:*:*:*:*

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