FKIE_CVE-2026-63867

Vulnerability from fkie_nvd - Published: 2026-07-19 15:16 - Updated: 2026-07-20 15:16
Severity
8.2 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: close TOCTOU race while computing rcv_wnd The MPTCP output path access locklessly the MPTCP-level ack_seq in multiple times, using possibly different values for the data_ack in the DSS option and to compute the announced rcv wnd for the same packet. Refactor the cote to avoid inconsistencies which may confuse the peer. Also ensure that the MPTCP level rcv wnd is updated only when the egress packet actually contains a DSS ack.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/options.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "301a33fd590c408a05c5df800e0cc1e6a8a2f8f8",
              "status": "affected",
              "version": "fa3fe2b150316b294f2c662653501273ff25bba8",
              "versionType": "git"
            },
            {
              "lessThan": "68364963e5baf03f16b4420292291f75c8f66497",
              "status": "affected",
              "version": "fa3fe2b150316b294f2c662653501273ff25bba8",
              "versionType": "git"
            },
            {
              "lessThan": "907ac6b1658e0277f979fcdfae2a753b495c1510",
              "status": "affected",
              "version": "fa3fe2b150316b294f2c662653501273ff25bba8",
              "versionType": "git"
            },
            {
              "lessThan": "c4f4cf60797974873dbc8e100144682a6f2f861f",
              "status": "affected",
              "version": "fa3fe2b150316b294f2c662653501273ff25bba8",
              "versionType": "git"
            },
            {
              "lessThan": "3b8cbba7c0ed31189c89f90be247b8973ffa79ef",
              "status": "affected",
              "version": "fa3fe2b150316b294f2c662653501273ff25bba8",
              "versionType": "git"
            },
            {
              "lessThan": "8f4f0a157e8436a05bf8c3670b24dbc258911c43",
              "status": "affected",
              "version": "fa3fe2b150316b294f2c662653501273ff25bba8",
              "versionType": "git"
            },
            {
              "lessThan": "8ab24fdebc369c0dfb90f82c1650b1e66662bb45",
              "status": "affected",
              "version": "fa3fe2b150316b294f2c662653501273ff25bba8",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/options.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.11"
            },
            {
              "lessThan": "5.11",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.94",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.36",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: close TOCTOU race while computing rcv_wnd\n\nThe MPTCP output path access locklessly the MPTCP-level ack_seq\nin multiple times, using possibly different values for the data_ack\nin the DSS option and to compute the announced rcv wnd for the same\npacket.\n\nRefactor the cote to avoid inconsistencies which may confuse the\npeer. Also ensure that the MPTCP level rcv wnd is updated only when\nthe egress packet actually contains a DSS ack."
    }
  ],
  "id": "CVE-2026-63867",
  "lastModified": "2026-07-20T15:16:52.690",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.2,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 4.2,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-19T15:16:53.617",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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