JTEKT TOYOPUC PLCs through 2022-04-29 do not ensure data integrity. They utilize the unauthenticated CMPLink/TCP protocol for engineering purposes, including downloading projects and control logic to the PLC. Control logic is downloaded to the PLC on a block-by-block basis with a given memory address and a blob of machine code. The logic that is downloaded to the PLC is not cryptographically authenticated, allowing an attacker to execute arbitrary machine code on the PLC's CPU module in the context of the runtime. In the case of the PC10G-CPU, and likely for other CPU modules of the TOYOPUC family, a processor without MPU or MMU is used and this no memory protection or privilege-separation capabilities are available, giving an attacker full control over the CPU.

JTEKT TOYOPUC PLCs through 2022-04-29 mishandle authentication. They utilize the CMPLink/TCP protocol (configurable on ports 1024-65534 on either TCP or UDP) for a wide variety of engineering purposes such as starting and stopping the PLC, downloading and uploading projects, and changing configuration settings. This protocol does not have any authentication features, allowing any attacker capable of communicating with the port in question to invoke (a subset of) desired functionality.

All versions of the afffected TOYOPUC-PC10 Series,TOYOPUC-Plus Series,TOYOPUC-PC3J/PC2J Series, TOYOPUC-Nano Series products may not be able to properly process an ICMP flood, which may allow an attacker to deny Ethernet communications between affected devices.

If Ethernet communication of the JTEKT Corporation TOYOPUC product series’ (TOYOPUC-PC10 Series: PC10G-CPU TCC-6353: All versions, PC10GE TCC-6464: All versions, PC10P TCC-6372: All versions, PC10P-DP TCC-6726: All versions, PC10P-DP-IO TCC-6752: All versions, PC10B-P TCC-6373: All versions, PC10B TCC-1021: All versions, PC10B-E/C TCU-6521: All versions, PC10E TCC-4737: All versions; TOYOPUC-Plus Series: Plus CPU TCC-6740: All versions, Plus EX TCU-6741: All versions, Plus EX2 TCU-6858: All versions, Plus EFR TCU-6743: All versions, Plus EFR2 TCU-6859: All versions, Plus 2P-EFR TCU-6929: All versions, Plus BUS-EX TCU-6900: All versions; TOYOPUC-PC3J/PC2J Series: FL/ET-T-V2H THU-6289: All versions, 2PORT-EFR THU-6404: All versions) are left in an open state by an attacker, Ethernet communications cannot be established with other devices, depending on the settings of the link parameters.