CVE-2021-20596

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-07-22 · updated 2026-06-17
Weakness: CWE-476

Description

NULL Pointer Dereference in MELSEC-F Series FX3U-ENET firmware version 1.14 and prior, FX3U-ENET-L firmware version 1.14 and prior and FX3U-ENET-P502 firmware version 1.14 and prior allows a remote unauthenticated attacker to cause a DoS condition in communication by sending specially crafted packets. Control by MELSEC-F series PLC is not affected and system reset is required for recovery.

Affected products

Mitsubishielectric Fx3U-Enet-L Firmware: through 1.14
Mitsubishielectric Fx3U-Enet-P502 Firmware: through 1.14
Mitsubishielectric Fx3U-Enet Firmware: through 1.14

References

https://jvn.jp/vu/JVNVU94348759/index.html
https://us-cert.cisa.gov/ics/advisories/icsa-21-201-01
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-006_en.pdf
https://jvn.jp/vu/JVNVU94348759/index.html
https://us-cert.cisa.gov/ics/advisories/icsa-21-201-01
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-006_en.pdf

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