An out‑of‑bounds read occurs in the EtherNet/IP TCP SendRRData Common Packet Format parser of EIPStackGroup OpENer. The CreateCommonPacketFormatStructure() function fails to verify that optional socket address items of type 0x8000 or 0x8001 are fully present before reading the fixed sockaddr structure. This vulnerability can allow a remote sender to craft malformed packets that trigger the buffer read, resulting in a service crash and denial of service to legitimate traffic.

The flaw affects OpENer version 2.3 and the master branch of the project up to commit 76b95cf. No other products or vendors are explicitly listed, so only the OpENer distribution was identified as vulnerable.

With a CVSS score of 7.5 the vulnerability is considered a high‑severity problem. The EPSS score is not available and the vulnerability is not listed in the CISA KEV catalog. Because the flaw resides in a network‑level packet parser, a remote attacker with network access can send crafted EtherNet/IP packets to an OpENer instance and trigger the crash, causing a denial of service. The attack requires only network connectivity and no local access privileges.