OpenPLC_v3 contains a heap-based buffer overflow in the getData() function in webserver/core/modbus_master.cpp. getData() reads characters between two delimiters into a caller-supplied buffer with no size parameter and no bounds check. In parseConfig() the function is invoked with the 100-byte heap-allocated MB_device.dev_name field. An authenticated attacker with access to the OpenPLC web interface can send a crafted HTTP POST to the /modbus endpoint with an oversized device_name value; the value is persisted to mbconfig.cfg and parsed on load, overflowing dev_name and overwriting adjacent struct fields (protocol at offset 108, dev_address at offset 109, ip_port at offset 210). A 200-byte payload writes 100 bytes past the allocation. The result is heap corruption leading to runtime crash and denial of service of the PLC process control loop, with attacker-controlled overwrite of adjacent configuration fields. The upstream repository was archived on 2026-04-04 and no fix is expected; the vendor has confirmed the issue does not affect OpenPLC Runtime v4.

A denial of service vulnerability exists in the ModbusTCP server functionality of OpenPLC _v3 a931181e8b81e36fadf7b74d5cba99b73c3f6d58. A specially crafted series of network connections can lead to the server not processing subsequent Modbus requests. An attacker can open a series of TCP connections to trigger this vulnerability.

/edit-user in webserver in OpenPLC Runtime 3 through 9cd8f1b allows authenticated users to upload arbitrary files (such as .html or .svg), and these are then publicly accessible under the /static URI.

An out-of-bounds read vulnerability exists in the OpenPLC Runtime EtherNet/IP PCCC parser functionality of OpenPLC_v3 b4702061dc14d1024856f71b4543298d77007b88. A specially crafted network request can lead to denial of service. An attacker can send a series of EtherNet/IP requests to trigger this vulnerability.This is the final instance of the incorrect comparison.

An out-of-bounds read vulnerability exists in the OpenPLC Runtime EtherNet/IP PCCC parser functionality of OpenPLC_v3 b4702061dc14d1024856f71b4543298d77007b88. A specially crafted network request can lead to denial of service. An attacker can send a series of EtherNet/IP requests to trigger this vulnerability.This is the first instance of the incorrect comparison.

A stack-based buffer overflow vulnerability exists in the OpenPLC Runtime EtherNet/IP parser functionality of OpenPLC _v3 b4702061dc14d1024856f71b4543298d77007b88. A specially crafted EtherNet/IP request can lead to remote code execution. An attacker can send a series of EtherNet/IP requests to trigger this vulnerability.

Multiple invalid pointer dereference vulnerabilities exist in the OpenPLC Runtime EtherNet/IP parser functionality of OpenPLC_v3 16bf8bac1a36d95b73e7b8722d0edb8b9c5bb56a. A specially crafted EtherNet/IP request can lead to denial of service. An attacker can send a series of EtherNet/IP requests to trigger these vulnerabilities.This instance of the vulnerability occurs within the `Protected_Logical_Write_Reply` function

Multiple invalid pointer dereference vulnerabilities exist in the OpenPLC Runtime EtherNet/IP parser functionality of OpenPLC_v3 16bf8bac1a36d95b73e7b8722d0edb8b9c5bb56a. A specially crafted EtherNet/IP request can lead to denial of service. An attacker can send a series of EtherNet/IP requests to trigger these vulnerabilities.This instance of the vulnerability occurs within the `Protected_Logical_Read_Reply` function