{
  "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-2021-25664",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-25664",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2021-04-22T20:42:20.000Z",
    "updatedAt": "2025-03-11T09:47:35.103Z",
    "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": "A vulnerability has been identified in Capital Embedded AR Classic 431-422 (All versions), Capital Embedded AR Classic R20-11 (All versions < V2303), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (All versions including affected IPv6 stack). The function that processes the Hop-by-Hop extension header in IPv6 packets and its options lacks any checks against the length field of the header, allowing attackers to put the function into an infinite loop by supplying arbitrary length values.",
      "affected": [
        {
          "vendor": "Siemens",
          "product": "Capital Embedded AR Classic 431-422",
          "defaultStatus": "unknown",
          "versions": [
            {
              "version": "0",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "*"
            }
          ]
        },
        {
          "vendor": "Siemens",
          "product": "Capital Embedded AR Classic R20-11",
          "defaultStatus": "unknown",
          "versions": [
            {
              "version": "0",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "V2303"
            }
          ]
        },
        {
          "vendor": "Siemens",
          "product": "Nucleus NET",
          "defaultStatus": "unknown",
          "versions": [
            {
              "version": "All versions",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Siemens",
          "product": "Nucleus ReadyStart V3",
          "defaultStatus": "unknown",
          "versions": [
            {
              "version": "0",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "V2017.02.4"
            }
          ]
        },
        {
          "vendor": "Siemens",
          "product": "Nucleus ReadyStart V4",
          "defaultStatus": "unknown",
          "versions": [
            {
              "version": "0",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "V4.1.0"
            }
          ]
        },
        {
          "vendor": "Siemens",
          "product": "Nucleus Source Code",
          "defaultStatus": "unknown",
          "versions": [
            {
              "version": "0",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "*"
            }
          ]
        }
      ]
    }
  }
}