CVE-2026-21660: Frick Quantum HD Information Disclosure

CVE-2026-21660 Overview

CVE-2026-21660 is a Hardcoded Credentials vulnerability affecting Frick Controls Quantum HD firmware versions 10.22 and prior. The vulnerability involves hardcoded email credentials stored as plaintext within the device firmware, classified under CWE-256 (Plaintext Storage of a Password) and CWE-522 (Insufficiently Protected Credentials). This security flaw can lead to unauthorized access, exposure of sensitive information, and potential misuse or full system compromise of affected industrial control systems.

Critical Impact

Attackers with local access to the firmware can extract hardcoded email credentials stored in plaintext, potentially gaining unauthorized access to email systems associated with the industrial control environment and enabling further attacks on connected infrastructure.

Affected Products

• Johnson Controls Frick Controls Quantum HD Firmware version 10.22 and prior
• Johnson Controls Frick Controls Quantum HD hardware devices

Discovery Timeline

• February 27, 2026 - CVE-2026-21660 published to NVD
• March 2, 2026 - Last updated in NVD database

Technical Details for CVE-2026-21660

Vulnerability Analysis

This vulnerability stems from insecure credential management practices in the Frick Controls Quantum HD firmware. Email credentials required for system notifications or reporting functions are embedded directly into the firmware image as plaintext strings. This implementation bypasses fundamental security principles that require sensitive credentials to be encrypted, obfuscated, or stored in protected memory regions.

The affected systems are industrial control devices used in refrigeration and HVAC applications, making this vulnerability particularly concerning from an operational technology (OT) security perspective. Exploitation requires local access to the firmware, either through physical access to the device or through extraction of the firmware image from update packages or device memory.

Root Cause

The root cause is improper credential storage design where email account credentials are hardcoded directly into the firmware binary as plaintext strings rather than using secure credential management techniques. This violates CWE-256 (Plaintext Storage of a Password) and CWE-522 (Insufficiently Protected Credentials) best practices.

The firmware developers likely implemented this approach for convenience during development or to simplify device configuration, but this practice creates a significant security risk. Once credentials are embedded in firmware, they cannot be easily changed and become accessible to anyone who can obtain the firmware image.

Attack Vector

The attack vector is local, requiring an attacker to have access to the firmware image or physical access to the device. An attacker could obtain the firmware through various means:

1. Firmware extraction - Using JTAG, UART, or SPI flash reading techniques to dump the firmware from a physical device
2. Update package analysis - Downloading firmware update packages from vendor websites or intercepting update traffic
3. Memory forensics - Accessing the device's file system or memory through debug interfaces

Once the firmware is obtained, the attacker can use standard binary analysis tools such as strings, binwalk, or hex editors to locate and extract the plaintext email credentials. These credentials could then be used to access email accounts associated with the industrial control system, potentially enabling social engineering attacks, information gathering, or further network compromise.

Detection Methods for CVE-2026-21660

Indicators of Compromise

• Unexpected login attempts or authentication events to email accounts associated with Frick Controls Quantum HD systems
• Anomalous outbound email traffic originating from or related to industrial control system infrastructure
• Evidence of firmware extraction attempts such as physical tampering or unauthorized debug interface connections
• Suspicious access patterns to email accounts that should only be used for automated system notifications

Detection Strategies

• Monitor authentication logs for email accounts used by Frick Controls Quantum HD systems for unauthorized access attempts
• Implement network monitoring to detect unexpected outbound connections from ICS/SCADA network segments
• Deploy physical security controls and tamper detection on Frick Controls devices to identify unauthorized access attempts
• Review email account activity for signs of credential misuse, such as emails not sent by the control system

Monitoring Recommendations

• Configure alerts for email account logins from unexpected IP addresses or geographic locations
• Implement audit logging on all systems that interact with Frick Controls Quantum HD devices
• Monitor for firmware extraction tools or techniques being used against devices in your environment
• Establish baseline behavior for email accounts associated with industrial control systems and alert on deviations

How to Mitigate CVE-2026-21660

Immediate Actions Required

• Contact Johnson Controls to determine availability of patched firmware versions and upgrade timelines
• Isolate affected Frick Controls Quantum HD devices on segmented network zones with restricted access
• Change passwords for any email accounts that may have been configured in the affected firmware
• Implement additional authentication controls (such as MFA) on email accounts associated with industrial control systems
• Review access logs for any signs of exploitation or unauthorized access attempts

Patch Information

Johnson Controls has released security guidance for this vulnerability. Administrators should consult the Johnson Controls Security Advisory for the latest patch information and recommended firmware versions. Additionally, CISA has published ICS Advisory ICSA-26-057-01 with detailed mitigation guidance for affected organizations.

Workarounds

• Implement network segmentation to restrict access to affected devices from untrusted networks
• Disable email notification features if not operationally required until patched firmware is available
• Use a dedicated email account with minimal permissions specifically for industrial control system notifications
• Apply physical security measures to prevent unauthorized access to device hardware and debug interfaces
• Monitor email accounts for suspicious activity and implement strict access controls

# Network segmentation example for ICS environments
# Create firewall rules to isolate Frick Controls devices
iptables -A INPUT -s 192.168.100.0/24 -d 192.168.200.0/24 -j DROP
iptables -A OUTPUT -s 192.168.200.0/24 -d 0.0.0.0/0 -p tcp --dport 25 -j DROP
iptables -A OUTPUT -s 192.168.200.0/24 -d 0.0.0.0/0 -p tcp --dport 587 -j DROP