CVE-2021-27661Network attack vector

Authenticated system-file access via crafted web messages

Published Jul 1, 2021 · Updated Sep 16, 2024

Improper privilege management in Johnson Controls Facility Explorer F4-SNC version 11 allows remote authenticated users to alter system files. The controller accepts specially crafted web messages and grants file-system access beyond the authenticated user's intended privilege level. A valid controller account and network access to its web interface are required; successful exploitation permits reading or modifying system files.

CVSS severity8.8
High
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper privilege management in Johnson Controls Facility Explorer F4-SNC version 11 allows remote authenticated users to alter system files. The controller accepts specially crafted web messages and grants file-system access beyond the authenticated user's intended privilege level. A valid controller account and network access to its web interface are required; successful exploitation permits reading or modifying system files.

The record

CVE
CVE-2021-27661
Published
Jul 1, 2021
Updated
Sep 16, 2024
Vendor
Johnson Controls
Product
Facility Explorer F4-SNC
Classifications
CWE-269, T1068
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=Facility Explorer SNC Series Supervisory Controllers version 11 11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Johnson Controls · Facility Explorer F4-SNCversion=Facility Explorer SNC Series Supervisory Controllers version 11 11

Published CVSS scores

8.8Johnson ControlsCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo