{"id":"CVE-2021-20596","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-20596","generatedAt":"2026-10-27T21:18:02.532Z","title":"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…","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.","published":"2021-07-22T12:15:08.000Z","lastModified":"2026-06-17T03:34:05.000Z","status":"Modified","sourceIdentifier":"Mitsubishielectric.Psirt@yd.MitsubishiElectric.co.jp","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-476"],"affected":["mitsubishielectric/fx3u-enet-l firmware","mitsubishielectric/fx3u-enet-p502 firmware","mitsubishielectric/fx3u-enet firmware"],"epss":{"score":0.02172,"percentile":0.82173,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (2.17%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://jvn.jp/vu/JVNVU94348759/index.html","tags":["Patch","Third Party Advisory"],"source":"Mitsubishielectric.Psirt@yd.MitsubishiElectric.co.jp"},{"url":"https://us-cert.cisa.gov/ics/advisories/icsa-21-201-01","tags":["Third Party Advisory"],"source":"Mitsubishielectric.Psirt@yd.MitsubishiElectric.co.jp"},{"url":"https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-006_en.pdf","tags":["Patch","Vendor Advisory"],"source":"Mitsubishielectric.Psirt@yd.MitsubishiElectric.co.jp"},{"url":"https://jvn.jp/vu/JVNVU94348759/index.html","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://us-cert.cisa.gov/ics/advisories/icsa-21-201-01","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-006_en.pdf","tags":["Patch","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-20596","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}