CVE-2021-27657

Name: CVE-2021-27657
Creator: NVD / NIST
Published: 2021-06-04T15:15:07.517+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 1.24%

Last modified Jun 17, 2026

CVE-2021-27657 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. Successful exploitation of this vulnerability could give an authenticated Metasys user an unintended level of access to the server file system, allowing them to access or modify system files by sending specifically crafted web messages to the Metasys system. This issue affects: Johnson Controls Metasys version 11.0 and prior versions.. EPSS estimates a 1.24% chance of exploitation in the next 30 days.

Description

Successful exploitation of this vulnerability could give an authenticated Metasys user an unintended level of access to the server file system, allowing them to access or modify system files by sending specifically crafted web messages to the Metasys system. This issue affects: Johnson Controls Metasys version 11.0 and prior versions.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

1.24%

65.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Johnsoncontrols	Metasys	<= 11.0

References

https://us-cert.cisa.gov/ics/advisories/icsa-21-159-01Third Party Advisory, US Government Resource
https://us-cert.gov/ics/advisoriesThird Party Advisory, US Government Resource
https://www.johnsoncontrols.com/cyber-solutions/security-advisoriesVendor Advisory
https://us-cert.cisa.gov/ics/advisories/icsa-21-159-01Third Party Advisory, US Government Resource
https://us-cert.gov/ics/advisoriesThird Party Advisory, US Government Resource
https://www.johnsoncontrols.com/cyber-solutions/security-advisoriesVendor Advisory

Timeline

Published: Jun 4, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-27657?

How severe is CVE-2021-27657?

CVE-2021-27657 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 1.24% probability of exploitation in the next 30 days.

How do I fix CVE-2021-27657?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-27657?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST