CVE-2026-67862 in Open62541
Summary
by MITRE • 08/05/2026
open62541 1.5.5 contains a buffer-overflow in the high-level attribute reading logic in src/client/ua_client_highlevel.c. This allows a remote attacker to cause a denial of service.
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Analysis
by VulDB Data Team • 08/05/2026
The open62541 library version 1.5.5 contains a critical buffer overflow vulnerability within its high-level attribute reading functionality located in the ua_client_highlevel.c source file. This vulnerability represents a fundamental flaw in memory management that occurs when processing attribute data from OPC UA servers, making it particularly dangerous for industrial control systems and IoT deployments that rely on this library for communication protocols.
The technical implementation of this buffer overflow stems from inadequate input validation and bounds checking within the client-side attribute reading logic. When the library processes attribute values returned by OPC UA servers, it fails to properly validate the size or length of incoming data before copying it into fixed-size buffers. This classic programming error allows an attacker to supply maliciously crafted attribute data that exceeds the allocated buffer capacity, resulting in memory corruption that can be exploited for arbitrary code execution or system instability.
This vulnerability operates at the application layer within the OPC UA communication stack and specifically targets the client-side high-level API functions designed to read node attributes. The attack vector is entirely remote, meaning an unauthenticated attacker can exploit this flaw by connecting to a vulnerable open62541-based client and sending specially crafted attribute data responses. The impact manifests primarily as denial of service conditions where the application crashes or becomes unresponsive, though the underlying memory corruption could potentially be leveraged for more severe exploitation scenarios.
From a cybersecurity perspective, this vulnerability aligns with CWE-121 which describes classic stack-based buffer overflow conditions and represents a significant risk to industrial IoT deployments that use open62541 for OPC UA client implementations. The ATT&CK framework categorizes this as a privilege escalation or denial of service technique where adversaries can disrupt system operations through memory corruption vulnerabilities. Organizations using this library in critical infrastructure environments face potential operational disruptions that could affect production processes, monitoring systems, and overall industrial control network stability.
The recommended mitigation strategy involves immediate patching to version 1.5.6 or later which contains the necessary buffer overflow protections and input validation fixes. System administrators should also implement network segmentation and access controls to limit exposure of vulnerable systems to untrusted networks. Additionally, monitoring for unusual attribute reading patterns and implementing intrusion detection systems can help identify potential exploitation attempts before they cause service disruption. Organizations should conduct comprehensive vulnerability assessments across all systems utilizing this library to ensure complete remediation and maintain operational security posture against similar memory corruption vulnerabilities.