CVE-2021-20596

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.

• CWE-476

• https://jvn.jp/vu/JVNVU94348759/index.htmlPatch, Third Party Advisory
• https://us-cert.cisa.gov/ics/advisories/icsa-21-201-01Third Party Advisory
• https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-006_en.pdfPatch, Vendor Advisory
• https://jvn.jp/vu/JVNVU94348759/index.htmlPatch, Third Party Advisory
• https://us-cert.cisa.gov/ics/advisories/icsa-21-201-01Third Party Advisory
• https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-006_en.pdfPatch, Vendor Advisory

Published

Jul 22, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
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