CVE-2021-27657Network attack vector

Authenticated system-file access via crafted web messages

Published Jun 4, 2021 · Updated Sep 17, 2024

Improper privilege management in Johnson Controls Metasys 11.0 and earlier allows remote authenticated users to access system files. The web-services layer accepts crafted messages that cross the caller's intended file-system authorization boundary. A password-protected Metasys local or Active Directory account is required; successful exploitation permits reading or modifying system files.

CVSS severity8.8
High
EPSS probability1.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper privilege management in Johnson Controls Metasys 11.0 and earlier allows remote authenticated users to access system files. The web-services layer accepts crafted messages that cross the caller's intended file-system authorization boundary. A password-protected Metasys local or Active Directory account is required; successful exploitation permits reading or modifying system files.

The record

CVE
CVE-2021-27657
Published
Jun 4, 2021
Updated
Sep 17, 2024
Vendor
Johnson Controls
Product
Metasys
Classifications
CWE-269, T0866
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=11.0 <=11.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Johnson Controls · Metasysversion=11.0 <=11.0

Published CVSS scores

8.8Johnson ControlsCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-269Improper Privilege Management
T0866Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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