FKIE_CVE-2026-63828

Vulnerability from fkie_nvd - Published: 2026-07-19 12:16 - Updated: 2026-07-20 15:16
Severity
8.4 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Summary
In the Linux kernel, the following vulnerability has been resolved: apparmor: mediate the implicit connect of TCP fast open sendmsg sendmsg()/sendto() with MSG_FASTOPEN is a combination of connect(2) and write(2): it opens the connection in the SYN. apparmor_socket_sendmsg() only checks AA_MAY_SEND, so a profile that grants send but denies connect lets a confined task open an outbound TCP/MPTCP connection that connect(2) would have refused, bypassing connect mediation. Mediate the implicit connect when MSG_FASTOPEN is set and a destination is supplied. Add it to apparmor_socket_sendmsg() (not the shared aa_sock_msg_perm() helper, which recvmsg also uses) and call aa_sk_perm() directly, mirroring the selinux and tomoyo fixes. sk_is_tcp() does not cover MPTCP fast open, so the SOCK_STREAM/IPPROTO_MPTCP arm is explicit.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/07b71c342382b854ab8030b244aeab6a7228ad7d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/45ebb934ea50b436ce49b2f159f090dab0d7fa28
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4a69b83045d3195d5b9a9b053ad840ddb2998b4e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4d587cd8a72155089a627130bbd4716ec0856e21
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7f57428ce00891d26b0f087ef754a4d820ec83aa
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/faea60deaa05c76f0772650f42eafde12bd39d93
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "security/apparmor/lsm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7f57428ce00891d26b0f087ef754a4d820ec83aa",
              "status": "affected",
              "version": "cf60af03ca4e71134206809ea892e49b92a88896",
              "versionType": "git"
            },
            {
              "lessThan": "faea60deaa05c76f0772650f42eafde12bd39d93",
              "status": "affected",
              "version": "cf60af03ca4e71134206809ea892e49b92a88896",
              "versionType": "git"
            },
            {
              "lessThan": "07b71c342382b854ab8030b244aeab6a7228ad7d",
              "status": "affected",
              "version": "cf60af03ca4e71134206809ea892e49b92a88896",
              "versionType": "git"
            },
            {
              "lessThan": "4a69b83045d3195d5b9a9b053ad840ddb2998b4e",
              "status": "affected",
              "version": "cf60af03ca4e71134206809ea892e49b92a88896",
              "versionType": "git"
            },
            {
              "lessThan": "45ebb934ea50b436ce49b2f159f090dab0d7fa28",
              "status": "affected",
              "version": "cf60af03ca4e71134206809ea892e49b92a88896",
              "versionType": "git"
            },
            {
              "lessThan": "4d587cd8a72155089a627130bbd4716ec0856e21",
              "status": "affected",
              "version": "cf60af03ca4e71134206809ea892e49b92a88896",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "security/apparmor/lsm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.6"
            },
            {
              "lessThan": "3.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.177",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "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\napparmor: mediate the implicit connect of TCP fast open sendmsg\n\nsendmsg()/sendto() with MSG_FASTOPEN is a combination of connect(2) and\nwrite(2): it opens the connection in the SYN. apparmor_socket_sendmsg()\nonly checks AA_MAY_SEND, so a profile that grants send but denies connect\nlets a confined task open an outbound TCP/MPTCP connection that connect(2)\nwould have refused, bypassing connect mediation.\n\nMediate the implicit connect when MSG_FASTOPEN is set and a destination\nis supplied. Add it to apparmor_socket_sendmsg() (not the shared\naa_sock_msg_perm() helper, which recvmsg also uses) and call aa_sk_perm()\ndirectly, mirroring the selinux and tomoyo fixes. sk_is_tcp() does not\ncover MPTCP fast open, so the SOCK_STREAM/IPPROTO_MPTCP arm is explicit."
    }
  ],
  "id": "CVE-2026-63828",
  "lastModified": "2026-07-20T15:16:49.453",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "NONE",
          "baseScore": 8.4,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.0,
        "impactScore": 5.8,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-19T12:16:56.110",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/07b71c342382b854ab8030b244aeab6a7228ad7d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/45ebb934ea50b436ce49b2f159f090dab0d7fa28"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4a69b83045d3195d5b9a9b053ad840ddb2998b4e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4d587cd8a72155089a627130bbd4716ec0856e21"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7f57428ce00891d26b0f087ef754a4d820ec83aa"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/faea60deaa05c76f0772650f42eafde12bd39d93"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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