Stack-based Buffer OverflowWeakness · CWE-121

CVE-2025-26386

HIGH · 7.1 CVSS v4.0 Published 2026-01-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Johnson Controls iSTAR Configuration Utility (ICU) has Stack-based Buffer Overflow vulnerability. This issue affects iSTAR Configuration Utility (ICU) version 6.9.7 and prior. Successful exploitation of this vulnerability could result in failure within the operating system of the machine hosting the ICU tool.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A stack-based buffer overflow vulnerability exists in Johnson Controls iSTAR Configuration Utility (ICU) version 6.9.7 and prior. The vulnerability occurs when the application handles input data that exceeds the boundaries of a stack-allocated buffer, potentially corrupting adjacent memory and causing operating system failure on the host machine.

MitigationUpgrade iSTAR Configuration Utility to a version beyond 6.9.7 that contains the security patch. If no patched version is available, consider compensating controls such as network segmentation and restricting access to the ICU tool to trusted personnel only.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
P
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate iSTAR Configuration Utility installation
    Search the system for files related to iSTAR ICU (e.g., istaricu.exe, iSTAR Configuration Utility in Program Files, or check the installation directory where Johnson Controls software is typically installed)
    Affected if The application is found installed on the system
  2. Determine installed version of iSTAR Configuration Utility
    Right-click the ICU executable, select Properties, and check the Version tab, or use the application's About/Help menu to view the version number
    Affected if The displayed version is 6.9.7 or any version prior to 6.9.7 (e.g., 6.9.6, 6.9.5, etc.)
  3. Verify the application is in active use
    Check if the iSTAR Configuration Utility has been recently launched or configured to run on the system; review any scheduled tasks or services related to ICU
    Affected if The application is present and has been used to configure iSTAR devices, as the vulnerability triggers when handling input data

The system is affected if iSTAR Configuration Utility version 6.9.7 or prior is installed and the application is used to process configuration data, since the stack-based buffer overflow occurs during input handling.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade iSTAR Configuration Utility to a version beyond 6.9.7 that contains the security patch. If no patched version is available, consider compensating controls such as network segmentation and restricting access to the ICU tool to trusted personnel only.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-26386 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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