What is the CVSS score of CVE-2026-21657?

CVE-2026-21657 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: 0.1%.

How to fix or mitigate CVE-2026-21657?

Within 24 hours: Identify all Frick Controls Quantum HD deployments in your environment and assess network exposure. Immediately isolate affected systems from internet-facing networks and restrict access to trusted administrators only. Within 7 days: Implement network segmentation to limit lateral movement, enable comprehensive logging on affected systems, and establish daily vulnerability scanning. Within 30 days: Contact Johnson Controls for patch availability and timeline; evaluate replacement or upgrade options if patch delays exceed acceptable risk tolerance; conduct threat hunt for indicators of compromise on affected systems.

Frick Controls Quantum Hd Firmware CVE-2026-21657

CRITICAL

Code Injection (CWE-94)

2026-02-27 productsecurity@jci.com

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 malicious input to unauthenticated endpoint
Exploit

Bypass input validation
Execution

Inject arbitrary code
Impact

Execute code with device privileges

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 earlier with accessible network interface; no authentication required. Vulnerability exploitable against default configurations where input parameters lack validation before code execution.
Impact	CVSS 9.8. Cumulative attack surface from three critical CVEs makes exploitation highly likely.
Exploit ScenarioDerived	Alternative code injection path for achieving RCE on the refrigeration controller.

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

No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Second code injection vulnerability in Johnson Controls Frick Controls Quantum HD. Separate attack vector from CVE-2026-21656, same critical impact on industrial refrigeration control.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:55 CVSS 9.8

Code injection in Johnson Controls Frick Quantum HD — third CVE.

RemediationAI

Apply all Johnson Controls security patches simultaneously.

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. Third critical vulnerability in the Quantum HD product, distinct vector.

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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

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 code injection vulnerability in Johnson Controls Frick Controls Quantum HD (CVSS 9.8) allows unauthenticated attackers to execute arbitrary code on affected systems. Organizations using this HVAC control platform face immediate risk of system compromise, operational disruption, and potential lateral movement into connected building management infrastructure. No patch is currently available from the vendor.

Business Impact: Severe

Compensating Controls

Network segmentation: isolate Quantum HD systems on dedicated VLAN with strict ingress/egress rules. Disable remote management and API access if not operationally critical. Implement Web Application Firewall (WAF) rules to block code injection payloads (evaluate for applicability to control protocols). Restrict administrative access via VPN with MFA only. Deploy intrusion detection/prevention (IDS/IPS) with signatures for code injection attempts. Monitor for suspicious process execution and outbound connections. Until vendor patch available, maintain manual backup HVAC controls and offline failover procedures.

Threat Intelligence Overview

EPSS Score

0.1%

Top 74% 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 0.1%

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.