What is the CVSS score of CVE-2026-21656?

CVE-2026-21656 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%.

Which versions of Frick Controls Quantum Hd Firmware are affected by CVE-2026-21656?

A critical code injection vulnerability (CVSS 9.8) affects Johnson Controls Frick Controls Quantum HD systems, allowing attackers to execute arbitrary code and potentially gain full system control.

How to fix or mitigate CVE-2026-21656?

Within 24 hours: Inventory all Frick Controls Quantum HD deployments and assess network exposure; immediately isolate affected systems or restrict network access to trusted administrators only. Within 7 days: Implement compensating controls including network segmentation, WAF rules blocking suspicious input patterns, and enhanced monitoring for exploitation attempts. Within 30 days: Establish vendor communication cadence for patch availability; evaluate alternative control solutions and develop incident response procedures specific to this vulnerability.

Frick Controls Quantum Hd Firmware CVE-2026-21656

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

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

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

CVE Published

Feb 27, 2026 - 09:16 nvd

CRITICAL 9.8

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.

AnalysisAI

Code injection in Johnson Controls Frick Controls Quantum HD allows unauthenticated remote code execution on industrial refrigeration systems. Second critical vulnerability in the Quantum HD product line.