CVE-2025-26382: iSTAR Configuration Utility Buffer Overflow

CVE-2025-26382 Overview

CVE-2025-26382 is a critical stack-based buffer overflow vulnerability affecting the Johnson Controls iSTAR Configuration Utility (ICU) tool. Under certain circumstances, the ICU tool could be exploited through a buffer overflow condition, potentially allowing attackers to execute arbitrary code or cause system instability on affected systems.

Critical Impact

This stack-based buffer overflow vulnerability (CWE-121) in the iSTAR Configuration Utility could allow remote attackers to execute arbitrary code or cause denial of service conditions on systems used for physical access control configuration.

Affected Products

• Johnson Controls iSTAR Configuration Utility (ICU)

Discovery Timeline

• April 24, 2025 - CVE-2025-26382 published to NVD
• April 29, 2025 - Last updated in NVD database

Technical Details for CVE-2025-26382

Vulnerability Analysis

This vulnerability is classified as a stack-based buffer overflow (CWE-121), which occurs when a program writes more data to a buffer located on the stack than what is allocated for that buffer. In the context of the iSTAR Configuration Utility, this overflow condition can be triggered under certain circumstances when processing input data.

The iSTAR Configuration Utility is a critical component used for configuring Johnson Controls iSTAR access control panels. These systems are commonly deployed in physical security infrastructure for managing building access, making this vulnerability particularly significant for organizations relying on iSTAR-based access control solutions.

The network-based attack vector indicates that exploitation does not require local access to the target system, and the vulnerability can be exploited without authentication or user interaction, significantly increasing the potential attack surface.

Root Cause

The root cause of CVE-2025-26382 is a stack-based buffer overflow (CWE-121) in the iSTAR Configuration Utility. This type of vulnerability typically occurs when:

• Input data is copied to a fixed-size stack buffer without proper bounds checking
• String manipulation functions are used without length validation
• Memory allocation sizes are calculated incorrectly, leading to undersized buffers

When exploited, stack-based buffer overflows can overwrite critical stack data including return addresses, allowing attackers to redirect program execution to malicious code.

Attack Vector

The vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker could craft malicious input designed to overflow the vulnerable buffer in the ICU tool. Successful exploitation could result in:

• Arbitrary code execution with the privileges of the ICU process
• Denial of service through application crashes
• Potential compromise of the underlying system used for access control configuration

The attack does not require authentication (PR:N) or user interaction (UI:N), and can be executed with low attack complexity (AC:L), making it particularly dangerous if exposed to untrusted networks.

Detection Methods for CVE-2025-26382

Indicators of Compromise

• Unexpected crashes or service interruptions of the iSTAR Configuration Utility
• Anomalous network traffic patterns targeting systems running the ICU tool
• Evidence of memory corruption or stack smashing in application logs
• Unauthorized processes spawned from the ICU application context

Detection Strategies

• Deploy network intrusion detection systems (IDS) with signatures for buffer overflow exploitation patterns targeting ICU
• Monitor endpoint detection and response (EDR) solutions for suspicious memory operations and process injection attempts
• Implement application-level logging to capture unusual input patterns or error conditions
• Use SentinelOne Singularity platform to detect and prevent exploitation attempts through behavioral AI analysis

Monitoring Recommendations

• Enable verbose logging on systems running the iSTAR Configuration Utility to capture potential exploitation attempts
• Monitor network traffic to and from ICU hosts for unusual volume or connection patterns
• Configure SIEM rules to alert on multiple ICU application crashes or restarts in short timeframes
• Implement file integrity monitoring on ICU installation directories to detect unauthorized modifications

How to Mitigate CVE-2025-26382

Immediate Actions Required

• Review the CISA ICS Advisory ICSA-25-114-05 for detailed mitigation guidance
• Isolate systems running the iSTAR Configuration Utility from untrusted networks
• Restrict network access to ICU hosts to authorized administrators only
• Monitor for available patches from Johnson Controls via their Security Advisory page

Patch Information

Organizations should monitor Johnson Controls security advisories for official patches addressing this vulnerability. The vendor advisory is available at the Johnson Controls Trust Center. CISA has published advisory ICSA-25-114-05 with additional guidance for affected organizations.

Given the critical nature of this vulnerability in industrial control systems used for physical security, organizations should prioritize patching once updates become available.

Workarounds

• Implement network segmentation to isolate ICU systems from general network traffic
• Use firewall rules to restrict access to ICU hosts to only authorized IP addresses and ports
• Deploy intrusion prevention systems (IPS) capable of detecting and blocking buffer overflow exploitation attempts
• Consider running the ICU tool only when needed for configuration tasks rather than as a persistent service

# Example firewall rule to restrict access to ICU systems (adjust IP ranges as needed)
# Restrict ICU access to management VLAN only
iptables -A INPUT -s 10.0.100.0/24 -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Log denied connection attempts for monitoring
iptables -A INPUT -p tcp --dport 443 -j LOG --log-prefix "ICU-DENIED: "