CVE-2026-21659
Published: 27 February 2026
Summary
CVE-2026-21659 is a high-severity Relative Path Traversal (CWE-23) vulnerability in Johnsoncontrols Frick Controls Quantum Hd Firmware. Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 44.7% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SC-7 (Boundary Protection) and SI-10 (Information Input Validation).
Deeper analysis
CVE-2026-21659 is an unauthenticated remote code execution (RCE) and information disclosure vulnerability stemming from a local file inclusion (LFI) flaw, tracked under CWE-23 and CWE-22. It affects Johnson Controls Frick Controls Quantum HD devices, specifically version 10.22 and prior. The vulnerability carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating critical severity due to its network accessibility, low complexity, and lack of prerequisites.
An unauthenticated attacker can exploit this LFI vulnerability remotely over the network to execute arbitrary code on the affected device, resulting in full system compromise. This also enables information disclosure, allowing access to sensitive data on the target system.
Mitigation details are outlined in advisories from CISA (ICSA-26-057-01) and Johnson Controls' trust center cybersecurity security advisories, available at the respective reference URLs. Security practitioners should consult these for patching instructions and workarounds applicable to Frick Controls Quantum HD devices.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9019
Vulnerability details
Unauthenticated Remote Code Execution and Information Disclosure due to Local File Inclusion (LFI) vulnerability in Johnson Controls Frick Controls Quantum HD allow an unauthenticated attacker to execute arbitrary code on the affected device, leading to full system compromise. This issue…
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affects Frick Controls Quantum HD: Frick Controls Quantum HD version 10.22 and prior.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Unauthenticated LFI in a network-accessible service on the device enables exploitation of public-facing application (T1190) for RCE and file and directory discovery (T1083) for information disclosure.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
SI-10 directly prevents LFI exploitation by requiring validation of inputs to block malicious file path traversals that enable unauthenticated RCE.
SI-2 ensures timely flaw remediation through patching the specific LFI vulnerability in Frick Controls Quantum HD version 10.22 and prior.
SC-7 implements boundary protection to restrict network access to the device, preventing remote unauthenticated exploitation of the LFI vulnerability.