An issue in the NetStaX EtherNet/IP Stack prior to v5.6.1 could allow a large Class 3 explicit-message request to exceed the application-side… (CVE-2026-78012)

The NetStaX EtherNet/IP Stack versions before 5.6.1 contain a buffer overflow vulnerability where a large Class 3 explicit-message request can exceed the application receive buffer silently. This flaw can cause memory corruption and device instability, potentially allowing remote attackers to exploit the condition without the originating device receiving an error indication. The vulnerability is identified as CWE-121 (Stack-based Buffer Overflow) and has a CVSS 3.1 score of 9.8, indicating critical severity. No patch or remediation information is provided in the available data.

Successful exploitation can result in memory corruption, leading to device crashes or potentially enabling remote code execution or other remote attacks. The originating device does not receive an error, which may allow stealthy exploitation. The critical CVSS score reflects high confidentiality, integrity, and availability impacts.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, monitor for updates from the vendor and consider limiting exposure of affected devices to untrusted networks.