{
  "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-2026-16221",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-16221",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-07-19T14:08:32.993Z",
    "updatedAt": "2026-07-20T13:53:42.583Z",
    "importedAt": "2026-10-24T01:57:55.771Z",
    "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": "fast-uri vulnerable to host confusion via literal backslash authority delimiter",
      "summary": "Impact: fast-uri versions from 2.3.1 through 4.1.0 (including the 3.x line up to 3.1.3 and the 2.x line up to 2.4.2) do not treat a literal backslash character (U+005C) as an authority delimiter. Node's native WHATWG URL parser, used by fetch, undici, and Node's http and https clients, normalizes the backslash to a forward slash for special schemes such as http, https, ws, wss, ftp, and file. As a result, the two parsers extract different hosts from the same input string. Applications that use fast-uri to enforce host-based policy such as allowlists, denylists, loopback or SSRF filtering, redirect validation, or outbound proxy routing before passing the same URL into Node's URL or fetch consumers can be steered to an unintended destination, including cloud metadata endpoints, loopback, or internal hosts. \n\nPatches: upgrade to fast-uri 4.1.1, 3.1.4, or 2.4.3.\n\nWorkarounds: none.",
      "affected": [
        {
          "vendor": "fast-uri",
          "product": "fast-uri",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "2.3.1",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "2.4.3"
            },
            {
              "version": "2.4.3",
              "status": "unaffected",
              "versionType": "semver"
            },
            {
              "version": "3.0.0",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "3.1.4"
            },
            {
              "version": "3.1.4",
              "status": "unaffected",
              "versionType": "semver"
            },
            {
              "version": "4.0.0",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "4.1.1"
            },
            {
              "version": "4.1.1",
              "status": "unaffected",
              "versionType": "semver"
            }
          ]
        }
      ]
    }
  }
}