{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2021-20611",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-20611",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2021-12-01T15:41:31.000Z",
    "updatedAt": "2024-08-03T17:45:44.828Z",
    "importedAt": "2026-10-24T01:56:26.894Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": null,
      "summary": "Improper Input Validation vulnerability in Mitsubishi Electric MELSEC iQ-R Series R00/01/02CPU, MELSEC iQ-R Series R04/08/16/32/120(EN)CPU, MELSEC iQ-R Series R08/16/32/120SFCPU, MELSEC iQ-R Series R08/16/32/120PCPU, MELSEC iQ-R Series R08/16/32/120PSFCPU, MELSEC iQ-R Series R16/32/64MTCPU, MELSEC iQ-R Series R12CCPU-V, MELSEC Q Series Q03UDECPU, MELSEC Q Series Q04/06/10/13/20/26/50/100UDEHCPU, MELSEC Q Series Q03/04/06/13/26UDVCPU, MELSEC Q Series Q04/06/13/26UDPVCPU, MELSEC Q Series Q12DCCPU-V, MELSEC Q Series Q24DHCCPU-V(G), MELSEC Q Series Q24/26DHCCPU-LS, MELSEC Q Series MR-MQ100, MELSEC Q Series Q172/173DCPU-S1, MELSEC Q Series Q172/173DSCPU, MELSEC Q Series Q170MCPU, MELSEC Q Series Q170MSCPU(-S1), MELSEC L Series L02/06/26CPU(-P), MELSEC L Series L26CPU-(P)BT and MELIPC Series MI5122-VW allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition by sending specially crafted packets. System reset is required for recovery.",
      "affected": [
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R00CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"24\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R01CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"24\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R02CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"24\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R04CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R08CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R16CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R32CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R120CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R04ENCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R08ENCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R16ENCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R32ENCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R120ENCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"57\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R08SFCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"26\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R16SFCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"26\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R32SFCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"26\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R120SFCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"26\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R08PCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"29\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R16PCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"29\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R32PCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"29\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R120PCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"29\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R08PSFCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"08\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R16PSFCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"08\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R32PSFCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"08\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R120PSFCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"08\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R16MTCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"23\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R32MTCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"23\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R64MTCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"23\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC iQ-R Series R12CCPU-V",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"16\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q03UDECPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q04UDEHCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q06UDEHCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q10UDEHCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q13UDEHCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q20UDEHCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q26UDEHCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q50UDEHCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q100UDEHCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q03UDVCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23071\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q04UDVCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23071\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q06UDVCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23071\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q13UDVCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23071\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q26UDVCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23071\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q04UDPVCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23071\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q06UDPVCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23071\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q13UDPVCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23071\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q26UDPVCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23071\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q12DCCPU-V",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"24031\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q24DHCCPU-V",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"24031\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q24DHCCPU-VG",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"24031\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q24DHCCPU-LS",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"24031\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q26DHCCPU-LS",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"24031\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series MR-MQ100",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"F\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q172DCPU-S1",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"W\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q173DCPU-S1",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"W\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q172DSCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"Y\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q173DSCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"Y\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q170MCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"W\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q170MSCPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"Y\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC Q Series Q170MSCPU-S1",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Operating system software version \"Y\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC L Series L02CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC L Series L06CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC L Series L26CPU",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC L Series L02CPU-P",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC L Series L06CPU-P",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC L Series L26CPU-P",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC L Series L26CPU-BT",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELSEC L Series L26CPU-PBT",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "The first 5 digits of serial No. \"23121\" and prior",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Mitsubishi Electric Corporation",
          "product": "MELIPC Series MI5122-VW",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "Firmware versions \"05\" and prior",
              "status": "affected"
            }
          ]
        }
      ]
    }
  }
}