CVE-2026-67866 in S2OPC
Summary
by MITRE • 08/06/2026
Buffer Overflow vulnerability in Systerel S2OPC 1.7.3 allows a remote attacker to cause a denial of service via the LockedStaMac_ProcessMsg_DeleteMonitoredItemsResponse and SOPC_StaMac_NewDeleteMonitoredItems in the client wrapper DeleteMonitoredItems path
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Analysis
by VulDB Data Team • 08/06/2026
The buffer overflow vulnerability in Systerel S2OPC 1.7.3 represents a critical security flaw that enables remote attackers to execute denial of service attacks against systems utilizing this OPC UA stack implementation. This vulnerability specifically manifests within the client wrapper functionality when processing DeleteMonitoredItems operations, where the LockedStaMac_ProcessMsg_DeleteMonitoredItemsResponse and SOPC_StaMac_NewDeleteMonitoredItems functions fail to properly validate input data lengths before copying them into fixed-size buffers. The flaw resides in the protocol stack's message handling mechanism that processes monitored item deletion requests from OPC UA clients, creating an exploitable condition where maliciously crafted payloads can exceed buffer boundaries.
The technical implementation of this vulnerability stems from insufficient bounds checking within the OPC UA client wrapper layer of Systerel S2OPC, which operates under the Common Weakness Enumeration classification of CWE-121. This weakness specifically addresses stack-based buffer overflow conditions that occur when data is copied into buffers without proper validation of input lengths against predefined buffer sizes. The affected functions process incoming DeleteMonitoredItemsResponse messages from OPC UA servers and attempt to store this data in internal structures without adequate size verification, allowing attackers to inject excessive data that overflows adjacent memory regions.
The operational impact of this vulnerability extends beyond simple denial of service scenarios as it can potentially lead to system instability and application crashes within OPC UA client applications. When exploited successfully, the buffer overflow corrupts stack memory and can cause the entire client application to terminate unexpectedly, disrupting industrial automation processes that depend on continuous OPC UA communication. This is particularly concerning in operational technology environments where OPC UA clients maintain critical connections to SCADA systems, distributed control systems, and industrial process monitoring platforms. The vulnerability affects any system running Systerel S2OPC 1.7.3 within the client wrapper DeleteMonitoredItems path, making it a widespread concern for organizations implementing OPC UA-based communication protocols in industrial control environments.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected Systerel S2OPC installations to version 1.8.0 or later, which contains the necessary fixes for buffer overflow conditions in the client wrapper functionality. Network segmentation and access controls should be implemented to limit exposure of OPC UA client applications to untrusted networks, reducing the attack surface available to potential adversaries. Additionally, monitoring and logging of OPC UA client communication patterns can help detect anomalous DeleteMonitoredItems operations that may indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability aligns with techniques categorized under T1499 - Endpoint Termination and T1566 - Phishing, as attackers could leverage this flaw to disrupt industrial control systems through targeted denial of service attacks. Organizations should also consider implementing intrusion detection systems specifically configured to identify malformed OPC UA messages that could indicate exploitation attempts, particularly those targeting monitored item deletion functionality within OPC UA client implementations.