CVE-2021-27458: Jtekt 2port-Efr Thu-6404 Firmware

High severity, CVSS 7.5. EPSS: 1.1% chance of exploitation in the next 30 days.

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.

Affected products

Jtekt 2port-Efr Thu-6404 Firmware: any version
Jtekt Fl/et-T-v2h Thu-6289 Firmware: any version
Jtekt PC10B-E/c Tcu-6521 Firmware: any version
Jtekt PC10B-P Tcc-6373 Firmware: any version
Jtekt PC10B Tcc-1021 Firmware: any version
Jtekt PC10E Tcc-4737 Firmware: any version
Jtekt PC10G-CPU Tcc-6353 Firmware: any version
Jtekt PC10GE Tcc-6464 Firmware: any version
Jtekt PC10P-Dp-Io Tcc-6752 Firmware: any version
Jtekt PC10P-Dp Tcc-6726 Firmware: any version
Jtekt PC10P Tcc-6372 Firmware: any version
Jtekt Plus 2p-Efr Tcu-6929 Firmware: any version
Jtekt Plus Bus-Ex Tcu-6900 Firmware: any version
Jtekt Plus CPU Tcc-6740 Firmware: any version
Jtekt Plus EFR2 Tcu-6859 Firmware: any version
Jtekt Plus Efr Tcu-6743 Firmware: any version
Jtekt Plus EX2 Tcu-6858 Firmware: any version
Jtekt Plus Ex Tcu-6741 Firmware: any version

Published 2021-04-19. Last modified 2026-06-17.