Summary
Successful exploitation of this vulnerability could allow a standard user to escalate privileges on the host machine.
The following versions of Johnson Controls CEM AC2000 are affected:
- CEM AC2000 12.0 (CVE-2026-21661)
- CEM AC2000 11.0 (CVE-2026-21661)
- CEM AC2000 10.6 (CVE-2026-21661)
| CVSS | Vendor | Equipment | Vulnerabilities |
|---|---|---|---|
| v3 8.7 | Johnson Controls Inc. | Johnson Controls CEM AC2000 | Uncontrolled Search Path Element |
Background
- Critical Infrastructure Sectors: Critical Manufacturing, Commercial Facilities, Government Services and Facilities, Transportation Systems, Energy
- Countries/Areas Deployed: Worldwide
- Company Headquarters Location: Ireland
Vulnerabilities
CVE-2026-21661
The affected product is vulnerable to DLL hijacking, which could allow an attacker to escalate standard user privileges on the host machine.
Affected Products
Johnson Controls CEM AC2000
Johnson Controls Inc.
Johnson Controls Inc. CEM AC2000: 12.0, Johnson Controls Inc. CEM AC2000: 11.0, Johnson Controls Inc. CEM AC2000: 10.6
known_affected
Remediations
Mitigation
Johnson Controls recommends users apply the following mitigations:
Mitigation
Upgrade CEM AC 2000 12.0 to 12.0 Release 10.
Mitigation
Upgrade CEM AC 2000 11.0 to 11.0 Release 9.
Mitigation
Upgrade CEM AC 2000 10.6 to 10.6 Release 3.
Mitigation
For more detailed mitigation instructions, please see Johnson Controls Product Security Advisory.
https://www.johnsoncontrols.com/trust-center/cybersecurity/security-advisories
Relevant CWE: CWE-427 Uncontrolled Search Path Element
Metrics
| CVSS Version | Base Score | Base Severity | Vector String |
|---|---|---|---|
| 3.1 | 8.7 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L |
Acknowledgments
- Tom Hulme of CSACyber reported this vulnerability to Johnson Controls
Legal Notice and Terms of Use
This product is provided subject to this Notification (https://www.cisa.gov/notification) and this Privacy & Use policy (https://www.cisa.gov/privacy-policy).
Recommended Practices
CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability.
Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
Locate control system networks and remote devices behind firewalls and isolating them from business networks.
When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices.
CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Str
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