{
  "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-2021-3493",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-3493",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2021-04-17T04:20:16.706Z",
    "updatedAt": "2025-10-21T23:25:48.908Z",
    "importedAt": "2026-10-24T01:56:32.228Z",
    "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": "The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.",
      "affected": [
        {
          "vendor": "Ubuntu",
          "product": "linux kernel",
          "versions": [
            {
              "version": "5.8 kernel",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "5.8.0-50.56"
            },
            {
              "version": "5.4 kernel",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "5.4.0-72.80"
            },
            {
              "version": "4.15 kernel",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "4.15.0-142.146"
            },
            {
              "version": "4.4 kernel",
              "status": "affected",
              "versionType": "custom",
              "lessThan": "4.4.0-209.241"
            }
          ]
        }
      ]
    }
  }
}