FKIE_CVE-2021-47593

Vulnerability from fkie_nvd - Published: 2024-06-19 15:15 - Updated: 2026-06-17 04:17
Severity
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: clear 'kern' flag from fallback sockets The mptcp ULP extension relies on sk->sk_sock_kern being set correctly: It prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, "mptcp", 6); from working for plain tcp sockets (any userspace-exposed socket). But in case of fallback, accept() can return a plain tcp sk. In such case, sk is still tagged as 'kernel' and setsockopt will work. This will crash the kernel, The subflow extension has a NULL ctx->conn mptcp socket: BUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0 Call Trace: tcp_data_ready+0xf8/0x370 [..]
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/451f1eded7f56e93aaf52eb547ba97742d9c0e97Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c26ac0ea3a91c210cf90452e625dc441adf3e549Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d6692b3b97bdc165d150f4c1505751a323a80717Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/451f1eded7f56e93aaf52eb547ba97742d9c0e97Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/c26ac0ea3a91c210cf90452e625dc441adf3e549Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/d6692b3b97bdc165d150f4c1505751a323a80717Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 5.16
linux linux_kernel 5.16
linux linux_kernel 5.16
linux linux_kernel 5.16
linux linux_kernel 5.16
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/protocol.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "451f1eded7f56e93aaf52eb547ba97742d9c0e97",
              "status": "affected",
              "version": "cf7da0d66cc1a2a19fc5930bb746ffbb2d4cd1be",
              "versionType": "git"
            },
            {
              "lessThan": "c26ac0ea3a91c210cf90452e625dc441adf3e549",
              "status": "affected",
              "version": "cf7da0d66cc1a2a19fc5930bb746ffbb2d4cd1be",
              "versionType": "git"
            },
            {
              "lessThan": "d6692b3b97bdc165d150f4c1505751a323a80717",
              "status": "affected",
              "version": "cf7da0d66cc1a2a19fc5930bb746ffbb2d4cd1be",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/protocol.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.6"
            },
            {
              "lessThan": "5.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.88",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "5.16",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "38A89EC4-168A-4514-A383-6B85436E12DE",
              "versionEndExcluding": "5.10.88",
              "versionStartIncluding": "5.6",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "11274E95-438A-449A-B100-01B2B0046669",
              "versionEndExcluding": "5.15.11",
              "versionStartIncluding": "5.11",
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            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:*",
              "matchCriteriaId": "357AA433-37E8-4323-BFB2-3038D6E4B414",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:*",
              "matchCriteriaId": "A73429BA-C2D9-4D0C-A75F-06A1CA8B3983",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:*",
              "matchCriteriaId": "F621B5E3-E99D-49E7-90B9-EC3B77C95383",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc4:*:*:*:*:*:*",
              "matchCriteriaId": "F7BFDCAA-1650-49AA-8462-407DD593F94F",
              "vulnerable": true
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            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc5:*:*:*:*:*:*",
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: clear \u0027kern\u0027 flag from fallback sockets\n\nThe mptcp ULP extension relies on sk-\u003esk_sock_kern being set correctly:\nIt prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, \"mptcp\", 6); from\nworking for plain tcp sockets (any userspace-exposed socket).\n\nBut in case of fallback, accept() can return a plain tcp sk.\nIn such case, sk is still tagged as \u0027kernel\u0027 and setsockopt will work.\n\nThis will crash the kernel, The subflow extension has a NULL ctx-\u003econn\nmptcp socket:\n\nBUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0\nCall Trace:\n tcp_data_ready+0xf8/0x370\n [..]"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mptcp: borrar el indicador \u0027kern\u0027 de los sockets de reserva La extensi\u00f3n mptcp ULP depende de que sk-\u0026gt;sk_sock_kern est\u00e9 configurado correctamente: impide que setsockopt(fd, IPPROTO_TCP, TCP_ULP, \"mptcp\", 6); de funcionar para sockets tcp simples (cualquier socket expuesto al espacio de usuario). Pero en caso de respaldo, aceptar() puede devolver un sk tcp simple. En tal caso, sk todav\u00eda est\u00e1 etiquetado como \u0027kernel\u0027 y setsockopt funcionar\u00e1. Esto bloquear\u00e1 el kernel. La extensi\u00f3n de subflujo tiene un socket NULL ctx-\u0026gt;conn mptcp: ERROR: KASAN: null-ptr-deref en subflow_data_ready+0x181/0x2b0 Seguimiento de llamadas: tcp_data_ready+0xf8/0x370 [..]"
    }
  ],
  "id": "CVE-2021-47593",
  "lastModified": "2026-06-17T04:17:50.150",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2021-47593",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2024-09-10T17:12:30.519015Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2024-06-19T15:15:53.890",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/451f1eded7f56e93aaf52eb547ba97742d9c0e97"
    },
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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      "url": "https://git.kernel.org/stable/c/c26ac0ea3a91c210cf90452e625dc441adf3e549"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/d6692b3b97bdc165d150f4c1505751a323a80717"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/451f1eded7f56e93aaf52eb547ba97742d9c0e97"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/c26ac0ea3a91c210cf90452e625dc441adf3e549"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
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      "url": "https://git.kernel.org/stable/c/d6692b3b97bdc165d150f4c1505751a323a80717"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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