{
  "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-2021-47591",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-47591",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2024-06-19T14:53:54.918Z",
    "updatedAt": "2026-05-11T13:57:30.264Z",
    "importedAt": "2026-10-24T01:56:36.661Z",
    "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": "mptcp: remove tcp ulp setsockopt support",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: remove tcp ulp setsockopt support\n\nTCP_ULP setsockopt cannot be used for mptcp because its already\nused internally to plumb subflow (tcp) sockets to the mptcp layer.\n\nsyzbot managed to trigger a crash for mptcp connections that are\nin fallback mode:\n\nKASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]\nCPU: 1 PID: 1083 Comm: syz-executor.3 Not tainted 5.16.0-rc2-syzkaller #0\nRIP: 0010:tls_build_proto net/tls/tls_main.c:776 [inline]\n[..]\n __tcp_set_ulp net/ipv4/tcp_ulp.c:139 [inline]\n tcp_set_ulp+0x428/0x4c0 net/ipv4/tcp_ulp.c:160\n do_tcp_setsockopt+0x455/0x37c0 net/ipv4/tcp.c:3391\n mptcp_setsockopt+0x1b47/0x2400 net/mptcp/sockopt.c:638\n\nRemove support for TCP_ULP setsockopt.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "d9e4c129181004ec94b315b0c9db5eeb09da75e6",
              "status": "affected",
              "versionType": "git",
              "lessThan": "3de0c86d42f841d1d64f316cd949e65c566f0734"
            },
            {
              "version": "d9e4c129181004ec94b315b0c9db5eeb09da75e6",
              "status": "affected",
              "versionType": "git",
              "lessThan": "404cd9a22150f24acf23a8df2ad0c094ba379f57"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "5.13",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "5.13"
            },
            {
              "version": "5.15.11",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "version": "5.16",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}