CVE-2026-51537: Opener Project Opener

Critical severity, CVSS 9.1. EPSS: 0.6% chance of exploitation in the next 30 days.

EIPStackGroup OpENer 2.3.0 (commit 76b95cf) has an out-of-bounds read issue in Connection Manager handling of ForwardOpen requests when processing short malformed packets. An attacker can send a valid ENIP outer frame carrying a malformed CIP ForwardOpen/LargeForwardOpen request, causing the parser to continue reading fields even when request data is insufficient. This issue is remotely triggerable via network traffic and does not require authentication.

Affected products

Published 2026-07-13. Last modified 2026-08-11.