CVE-2026-21661

Local privilege escalation via DLL search hijacking

Published May 6, 2026 · Updated May 6, 2026

DLL hijacking in AC2000 10.6 before release 10, 11.0 before release 9, and 12 before release 3 allows local users to escalate privileges. Johnson Controls identifies DLL search-path resolution as the locus but does not disclose the affected executable, DLL name, or writable directory. A standard local account and the ability to place a crafted DLL in the searched location are required; successful exploitation executes arbitrary code with elevated host privileges.

CVSS severity8.4
High
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DLL hijacking in AC2000 10.6 before release 10, 11.0 before release 9, and 12 before release 3 allows local users to escalate privileges. Johnson Controls identifies DLL search-path resolution as the locus but does not disclose the affected executable, DLL name, or writable directory. A standard local account and the ability to place a crafted DLL in the searched location are required; successful exploitation executes arbitrary code with elevated host privileges.

The record

CVE
CVE-2026-21661
Published
May 6, 2026
Updated
May 6, 2026
Vendor
Johnson Controls
Product
AC2000
Classifications
CWE-427, CAPEC-38, T1574.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 2026Record 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=10.6 <release 10
  2. Affected versionversion=11.0 <release 9
  3. Affected versionversion=12 <release 3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Johnson Controls · AC2000version=10.6 <release 10; version=11.0 <release 9; version=12 <release 3

Published CVSS scores

8.4Johnson ControlsCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-427Uncontrolled Search Path Element
CAPEC-38Leveraging/Manipulating Configuration File Search Paths
T1574.001Hijack Execution Flow: DLL

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

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Your stack

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