Is CVE-2026-18790 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-18790 being exploited in the wild.

How severe is CVE-2026-18790?

Low severity, with a CVSS score of 3.3, published 4 August 2026.

Is there a fix for CVE-2026-18790?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-18790 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-18790?

Check whether you run Systerel S2OPC at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-18790: Systerel S2OPC out-of-bounds read in DeleteMonitoredItemsResponse handler

CVE-2026-18790 · Severity: low · CVSS 3.3 · Published 2026-08-04

Systerel S2OPC is an OPC UA (industrial communications) client library used to integrate manufacturing and automation systems. A malicious OPC UA server—or an attacker intercepting network traffic—can crash the client application by sending a specially crafted response with mismatched result counts, causing the library to read memory beyond allocated bounds. This results in denial of service to any application using the affected S2OPC client wrapper.

Technologies: Systerel S2OPC. Vendors: Systerel.

Quick answers

Is CVE-2026-18790 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-18790 being exploited in the wild.
How severe is CVE-2026-18790?: Low severity, with a CVSS score of 3.3, published 4 August 2026.
Which products and versions are affected?: Systerel S2OPC up to 1.7.3.
Is there a fix for CVE-2026-18790?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-18790 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-18790?: Check whether you run Systerel S2OPC at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is an out-of-bounds read in the DeleteMonitoredItemsResponse message handler (LockedStaMac_ProcessMsg_DeleteMonitoredItemsResponse in state_machine.c). The client wrapper processes the server's response using the `NoOfResults` field as a loop bound to iterate over results, but does not validate that this count matches the number of monitored item IDs stored in the corresponding client request. A malicious server can send more results than originally requested, causing the loop to read beyond the allocated array bounds. The attack is network-reachable via normal OPC UA session workflow (CreateSession, ActivateSession, CreateSubscription, CreateMonitoredItems, DeleteMonitoredItems) and reliably crashes the process. The vulnerability affects S2OPC up to version 1.7.3; vendor response status unknown.

Affected products

Systerel S2OPC up to 1.7.3

Timeline

2026-08-04: disclosed
other: Public exploit available (PoC shared on GitHub)

References

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