{
  "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-2021-25663",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-25663",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2021-04-22T20:42:20.000Z",
    "updatedAt": "2025-03-11T09:47:33.806Z",
    "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 IPv6 headers does not check the lengths of extension header options, allowing attackers to put this function into an infinite loop with crafted 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": "*"
            }
          ]
        }
      ]
    }
  }
}