CVE-2025-26386VulnerabilityPublished 28 Jan 2026

CVE-2025-26386: Johnson Controls iSTAR Configuration Utility (ICU) · Stack-based Buffer Overflow

Affects Johnson Controls iSTAR Configuration Utility (ICU)Source CVE Database V5

Not known to be exploited · CVSS 7.1 High.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

7.1High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: Passive
Vulnerable system confidentiality: None
Vulnerable system integrity: Low
Vulnerable system availability: High
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: Passive: Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker’s payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: High: There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Johnson ControlsiSTAR Configuration Utility (ICU)	Affected =iSTAR Configuration Utility (ICU) tool version 6.9.7 and prior	Fixed in–

AI-suggested

1. Immediately restrict network access to the iSTAR Configuration Utility to trusted administrators and management networks only, using firewalls and network segmentation. 2. Implement strict input validation and monitoring on systems running the ICU tool to detect anomalous or malformed configuration data. 3. Educate users and administrators to avoid opening untrusted or suspicious configuration files or inputs that could trigger the overflow. 4. Monitor security advisories from Johnson Controls for patches or updates addressing this vulnerability and plan for rapid deployment once available. 5. Employ endpoint protection solutions capable of detecting buffer overflow exploitation techniques and unusual process behavior related to the ICU tool. 6. Conduct regular security audits and penetration testing focused on physical security management systems to identify potential exploitation attempts. 7. Consider deploying intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics targeting buffer overflow attempts against the ICU tool. 8. Maintain comprehensive logging and alerting on ICU-related activities to facilitate rapid incident response. 9. If possible, isolate the ICU tool environment from general enterprise networks to limit exposure. 10. Develop and test incident response plans specific to physical security system compromises.

Description

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.

Impact

For European organizations, the impact of CVE-2025-26386 can be severe. Johnson Controls iSTAR systems are commonly used in physical access control for corporate offices, government buildings, transportation hubs, and critical infrastructure such as energy and utilities. Exploitation could allow attackers to execute arbitrary code on the configuration utility, potentially leading to unauthorized changes in access control policies, disabling of security mechanisms, or full compromise of the physical security management system. This undermines both physical and cyber security, increasing the risk of unauthorized facility access, data breaches, and operational disruptions. The vulnerability could also be leveraged as a foothold for lateral movement within enterprise networks. Given the critical nature of affected environments, successful exploitation could have cascading effects on safety, compliance, and business continuity. The absence of known exploits currently provides a window for proactive defense, but the high severity and ease of exploitation necessitate urgent attention.

CWE-121Stack-based Buffer Overflow (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #14
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Implementation
Implement and perform bounds checking on input.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 28 Jan 2026, 11:50 UTC

WeaknessesCWE-121

Technical details

References

Community reviews

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