Security readout for executives and security teams
Plain-English summary
CVE-2026-21656 affects Johnson Controls Frick Controls Quantum HD industrial controllers, version 10.22 and prior. A remote attacker may be able to cause code injection before login due to insufficient input validation. This is high business priority where these devices support refrigeration or industrial operations, especially if reachable from untrusted networks.
Executive priority
Treat as high priority for OT environments using affected Frick Quantum HD controllers. The main concern is unauthenticated remote code injection that could affect device integrity or availability. Prioritize sites where these systems support critical refrigeration or production processes, or where access is not tightly segmented.
Technical view
The issue is CWE-94 improper control of code generation. The CVSS 4.0 score is 8.8, with network attack vector, low complexity, no privileges, and no user interaction. Reported impacts are high integrity and availability impact to the vulnerable device. The CVE states the condition occurs before authentication in certain parameters.
Likely exposure
Exposure is limited to organizations using Frick Controls Quantum HD version 10.22 or prior. Risk is materially higher if management interfaces or related services are reachable from corporate, remote access, vendor, or internet-facing networks. The source bundle does not identify other Johnson Controls products as affected.
Exploitation context
CISA KEV status is false in the provided data, and the bundle does not cite active exploitation. However, the vulnerability is remotely reachable, unauthenticated, low-complexity, and affects industrial control equipment, making it important to assess quickly.
Researcher notes
Evidence is limited to the CVE record and advisory references. The bundle identifies affected versions and CVSS characteristics but does not include exploit details, proof of exploitation, or a specific patch version. Avoid assuming broader product impact without Johnson Controls or CISA confirmation.
Mitigation direction
- Identify all Frick Controls Quantum HD assets and versions.
- Check Johnson Controls security advisories for the vendor-approved fix or mitigation.
- Review CISA ICS advisory ICSA-26-057-01 for defensive guidance.
- Restrict access to affected devices from untrusted networks.
- Place affected controllers behind appropriate network segmentation and monitoring.
- Prioritize remediation for internet-reachable or remotely accessible systems.
Validation and detection
- Confirm whether each device is Frick Controls Quantum HD version 10.22 or prior.
- Verify whether device access is possible from untrusted or remote networks.
- Check asset inventories, engineering workstations, and OT network diagrams.
- Review vendor and CISA advisories for updated affected-version and remediation details.
- Monitor device and network logs for unusual unauthenticated requests or unexpected behavior.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-21656 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.8 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
8.8HighVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Source materials
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.