CVE-2026-75348 in OpENer
Summary
by MITRE • 10/09/2026
An out-of-bounds read vulnerability exists in EIPStackGroup OpENer v2.3 and master up to commit 76b95cf in the EtherNet/IP TCP SendRRData Common Packet Format parser. The issue occurs in CreateCommonPacketFormatStructure() when it parses recognized optional socket address information items of type 0x8000 or 0x8001 without first validating that the remaining CPF buffer contains the complete fixed sockaddr structure. This allows a remote attacker to cause a denial of service.
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Analysis
by VulDB Data Team • 10/09/2026
The vulnerability identified in EIPStackGroup OpENer versions prior to commit 76b95cf, specifically affecting version 2.3 and earlier master branches, represents a critical memory safety flaw within the EtherNet/IP protocol stack implementation. This issue is located in the TCP SendRRData Common Packet Format parser, which is responsible for processing incoming data structures that define how remote devices communicate over industrial Ethernet networks. The specific point of failure occurs during the execution of the CreateCommonPacketFormatStructure function, where the software attempts to parse optional socket address information items identified by type codes 0x8000 or 0x8001. These item types are part of the EtherNet/IP specification and are used to convey network addressing details necessary for establishing communication sessions between industrial control system components.
The core technical flaw is an out-of-bounds read condition resulting from a lack of boundary validation before memory access. When the parser encounters these specific optional socket address items, it proceeds directly to interpret the data as a fixed sockaddr structure without first verifying that the remaining buffer contains sufficient bytes to accommodate the entire structure. In C-based implementations like OpENer, which are common in embedded industrial systems, failing to check the length of available data against the size of the expected structure leads to reading memory beyond the allocated buffer limits. This behavior violates fundamental principles of secure coding and aligns with CWE-125, Out-of-bounds Read, where software reads past the end of a buffer or array.
From an operational perspective, this vulnerability allows for remote exploitation by any network actor capable of sending crafted EtherNet/IP packets to the affected device. Because the flaw triggers during standard protocol parsing routines, it does not require complex authentication or specific trigger conditions beyond reaching the vulnerable code path with malformed input. The immediate consequence is a denial of service condition. Depending on the underlying operating system and memory management policies, an out-of-bounds read may cause the application to crash due to segmentation faults or access violations, leading to temporary unavailability of the industrial device. In some scenarios, if sensitive data resides in adjacent memory regions that are inadvertently exposed by this read operation, it could potentially lead to information disclosure, although the primary reported impact is service disruption.
This vulnerability maps directly to MITRE ATT&CK technique T1498, Network Denial of Service, as an attacker can leverage this flaw to disrupt industrial operations by forcing connected devices offline. Furthermore, it relates to CWE-20, Improper Input Validation, since the root cause is the failure to validate that incoming data conforms to expected structural constraints before processing. The absence of length checks for optional fields in protocol parsers is a common pattern in legacy and embedded systems where performance optimization sometimes inadvertently sacrifices security rigor.
Mitigation strategies should prioritize immediate patching if an updated version of OpENer containing commit 76b95cf or later is available, as this commit reportedly addresses the validation logic. For environments unable to upgrade immediately, network segmentation is a critical compensating control. Placing EtherNet/IP traffic behind firewalls that inspect industrial protocols can prevent malicious packets from reaching vulnerable devices. Additionally, implementing strict input filtering at the network perimeter to drop malformed or oversized frames before they reach the application layer can reduce exposure. Developers maintaining custom builds of OpENer must ensure that all optional fields in Common Packet Format structures are validated for length against the remaining buffer size prior to any memory access operations involving fixed-size structures like sockaddr.