A heap‑based out‑of‑bounds write occurs in the server‑side EventFilter handling of CreateMonitoredItems in S2OPC 1.7.3. The flaw allows an attacker that can send a crafted request to the server to overwrite memory beyond the intended buffer, leading to arbitrary code execution on the host that runs the S2OPC server. The impact is a complete compromise of confidentiality, integrity, and availability of the affected system.

The vulnerable component is the S2OPC server version 1.7.3. No other vendor or product versions are listed, and the product name is not specified beyond the S2OPC library. Systems running this exact library version should consider themselves impacted.

The vulnerability is exploitable remotely over the network via a CreateMonitoredItems request containing a malformed EventFilter. No authentication or privileged state is required, so any party that can reach the server may trigger the exploit. Although an EPSS score is not available and the issue is not listed in CISA KEV, the nature of the flaw (an out‑of‑bounds write that grants code execution) typically indicates a high severity. The likelihood of exploitation is considered non‑negligible for exposed services. The attack vector is inferred to be remote due to the network‑based service involved.