CVE-2026-82944 in SOEM
Summary
by MITRE • 10/26/2026
SOEM version 2.0.0 and earlier contains a vulnerability in multi-segment data transfers where a malicious device can overflow memory buffers. The software checks the total size only once at the beginning, but doesn't track the cumulative size as multiple segments arrive. An attacker can declare a small initial size to pass validation, then send additional segments that exceed the allocated buffer. This allows the attacker to write controlled data beyond buffer boundaries, potentially enabling code execution.
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Analysis
by VulDB Data Team • 10/26/2026
The vulnerability identified in SOEM versions 2.0.0 and earlier represents a critical flaw within the implementation of multi-segment EtherCAT data transfers, specifically categorized under CWE-120 as a Buffer Overflow without bounds checking during memory copy operations. This security defect arises from an inadequate validation strategy employed by the software when handling fragmented network packets. In standard Ethernet-based industrial protocols like EtherCAT, large data payloads are often segmented to facilitate transmission over networks with limited Maximum Transmission Unit sizes. The SOEM library, which serves as a foundational component for many open-source EtherCAT master implementations, fails to enforce strict size constraints across these individual segments. Instead of validating the integrity and total volume of the incoming data stream against pre-allocated buffer limits at every stage of reception, the software performs a singular check on the initial segment's declared size. This architectural oversight creates a significant attack surface where an adversary can exploit the discrepancy between the validated header information and the actual cumulative payload size.
From a technical perspective, the flaw operates by allowing an attacker to manipulate the segmentation process to bypass memory safety checks. When a malicious device initiates a connection or data exchange with the vulnerable SOEM implementation, it transmits an initial segment that declares a small total message length, thereby passing the one-time validation check and securing allocation of a correspondingly sized buffer in system memory. However, subsequent segments sent by the attacker do not adhere to this declared limit. By transmitting additional data packets that exceed the boundaries of the initially allocated buffer, the application writes data into adjacent memory regions. This out-of-bounds write operation corrupts heap metadata or overwrites critical control structures such as return addresses and function pointers stored on the stack. The lack of cumulative size tracking means the software remains unaware that it is processing more data than permitted by its initial security assessment, leading to a classic buffer overflow condition that compromises memory integrity.
The operational impact of this vulnerability is severe, potentially granting an attacker arbitrary code execution capabilities within the context of the process running SOEM. In industrial control environments where EtherCAT masters are frequently deployed on systems with elevated privileges or direct access to hardware resources, successful exploitation can lead to complete system compromise. An adversary could leverage this flaw to inject and execute malicious shellcode, effectively taking control of the master station. This level of access allows for the manipulation of connected slave devices, disruption of production lines, theft of sensitive operational data, or even physical damage if the compromised controller issues unsafe commands to actuators or motors. The attack vector is typically remote but requires proximity to the network segment where the EtherCAT communication occurs, often necessitating a man-in-the-middle position or direct access to the industrial Ethernet switch fabric.
This vulnerability aligns with MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter sub-techniques if used for post-exploitation activities following initial code execution. It also reflects weaknesses associated with CWE-20 Improper Input Validation, as the system fails to correctly validate data against expected constraints during multi-stage processing. To mitigate this risk, developers must update SOEM to versions that implement rigorous validation of each segment's size relative to a running total or strict buffer limits. Security patches should enforce bounds checking on every incoming packet fragment rather than relying solely on initial header assertions. Additionally, network segmentation and the deployment of industrial firewalls can help isolate EtherCAT master stations from untrusted networks, reducing the likelihood of an attacker reaching the vulnerable service layer. Implementing memory protection mechanisms such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) may also mitigate the success rate of exploitation attempts by making it more difficult to reliably target specific memory locations for code execution.