CVE-2026-67867 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 Alarm/Conditions wrapper when processing PublishResponse EventNotificationList data
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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 through carefully crafted malicious data within the Alarm/Conditions wrapper functionality. This vulnerability specifically manifests when the software processes PublishResponse EventNotificationList data, creating an opportunity for attackers to exploit memory handling inconsistencies in the OPC UA implementation. The flaw stems from inadequate input validation and bounds checking mechanisms within the event processing pipeline, where the system fails to properly verify the size and structure of incoming notification data before attempting to store it in allocated memory buffers.
The technical nature of this vulnerability aligns with CWE-121, which describes buffer overflow conditions occurring when insufficient space is allocated for data storage or when input validation fails to prevent oversized data from being written into fixed-length buffers. In the context of OPC UA implementations like Systerel S2OPC, this issue particularly affects the EventNotificationList processing subsystem where multiple event notifications are handled in sequence. When an attacker crafts a malicious PublishResponse containing oversized or malformed EventNotificationList entries, the system's memory allocation routines become overwhelmed, leading to stack corruption or heap overflow conditions that ultimately result in application termination or system instability.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially enable more sophisticated attack vectors when combined with other exploitation techniques. Remote attackers who successfully trigger this buffer overflow can cause the OPC UA server to crash repeatedly, disrupting industrial control systems and automation processes that depend on reliable communication between devices and supervisory applications. The vulnerability affects systems where Systerel S2OPC is deployed as a server component in industrial environments, including manufacturing control systems, energy management platforms, and process automation networks where continuous operation is critical for safety and productivity.
Mitigation strategies should focus on implementing proper input validation controls and memory management practices within the OPC UA implementation. Organizations should prioritize immediate patching of affected Systerel S2OPC installations to version 1.7.4 or later, which includes fixes for the buffer overflow conditions in EventNotificationList processing. Network segmentation and access control measures can help limit exposure by restricting direct network access to OPC UA servers from untrusted networks, while monitoring systems should be deployed to detect anomalous PublishResponse patterns that might indicate attempted exploitation. The vulnerability also highlights the importance of following security guidelines from organizations like NIST and CERT/CC regarding secure coding practices for industrial communication protocols, particularly in environments where OPC UA is used for critical infrastructure applications. Additionally, implementing defensive measures such as address space layout randomization and stack canaries can provide additional layers of protection against exploitation attempts, though these should be complemented with proper software updates and configuration hardening procedures that align with the ATT&CK framework's recommendations for securing industrial control systems.