What is the CVSS score of CVE-2026-21658?

CVE-2026-21658 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.2%.

How to fix or mitigate CVE-2026-21658?

Within 24 hours: Identify and inventory all Frick Controls Quantum HD systems in your environment and isolate them from untrusted networks if operationally feasible. Within 7 days: Implement network segmentation to restrict access to these systems and enable enhanced monitoring for suspicious activity. Within 30 days: Contact Johnson Controls for patches or supported workarounds, and develop a remediation plan including potential system replacement if patches remain unavailable.

Frick Controls Quantum Hd Firmware CVE-2026-21658

CRITICAL

Code Injection (CWE-94)

2026-02-27 productsecurity@jci.com

RCE Code Injection Frick Controls Quantum Hd Firmware Johnsoncontrols

9.8

CVSS 3.1 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Send crafted HTTP request to unauthenticated endpoint
Exploit

Inject malicious code into unvalidated parameter
Execution

Execute arbitrary code on Quantum HD device
Impact

Gain full system compromise

Vulnerability Assessment

Weakness	CWE CWE-94 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Code injection prevention, sandbox exec MITRE ATT&CK 2 techniques across 2 tactics: Execution, Initial Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	Johnson Controls Frick Controls Quantum HD version 10.22 or prior with network accessibility. No authentication required. Vulnerable parameters accept unvalidated input before authentication checks occur.
Impact	CVSS 9.8, EPSS 0.25%. Unauthenticated RCE on industrial refrigeration controllers used in commercial/industrial environments.
Exploit ScenarioDerived	Attacker exploits unauthenticated code injection to gain complete control of Quantum HD controller, manipulates refrigeration parameters for physical impact or uses as OT network pivot.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.

No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Unauthenticated remote code execution via code injection in Johnson Controls Frick Controls Quantum HD. Fourth critical vulnerability — this one explicitly noted as unauthenticated RCE.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:55 CVSS 9.8

Unauthenticated RCE in Johnson Controls Frick Quantum HD — fourth CVE.

RemediationAI

Highest priority ICS patch. Apply immediately and verify network isolation of all Frick controllers.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

CWE-94 with explicit unauthenticated access. Most severe of the Quantum HD vulnerabilities.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionCVE.org

Unauthenticated Remote Code Execution i.e Improper Control of Generation of Code ('Code Injection') vulnerability in Johnson Controls Frick Controls Quantum HD allows Code Injection. Insufficient validation of input in certain parameters may permit unexpected actions, which could impact the security of the device before authentication occurs.This issue affects Frick Controls Quantum HD version 10.22 and prior.

Executive ViewAI

Why It Matters

A critical unauthenticated remote code execution vulnerability in Johnson Controls Frick Controls Quantum HD poses immediate risk to any organization running this equipment. Attackers can execute arbitrary code without authentication, potentially compromising HVAC systems, facility operations, and dependent infrastructure.

Business Impact: Severe

Compensating Controls

Implement network segmentation to restrict access to Quantum HD systems from untrusted networks. Deploy WAF rules blocking unexpected input patterns to the vulnerable endpoint. Disable remote access functionality if operationally feasible. Enforce strict firewall rules limiting ingress to management ports. Monitor for suspicious connections and code execution attempts. Disable unnecessary features or services. Consider air-gapping critical systems or implementing a proxy with input validation until patches are available.

Threat Intelligence Overview

EPSS Score

0.2%

Top 52% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC No

EPSS 0.2%

Patch available No

Active threat No

Deciding rule

CRITICAL severity

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Out-of-Cycle

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

Very High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +49

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.

Remote Code Execution CRITICAL

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.