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apparmor: mediate the implicit connect of TCP fast open sendmsg

Type: advisorySource: OSV1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-63828

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:CVE-2026-63828

Kernel

Source reference: /affected/1/package/name

Affected versions
Not stated in this record
Fixed versions
5.10.261

Source reference: /affected/1/ranges

5.15.212

Source reference: /affected/1/ranges

6.1.177

Source reference: /affected/1/ranges

6.6.144

Source reference: /affected/1/ranges

6.12.95

Source reference: /affected/1/ranges

6.18.38

Source reference: /affected/1/ranges

7.1.3

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
        "type": "GIT",
        "events": [
          {
            "introduced": "cf60af03ca4e71134206809ea892e49b92a88896"
          },
          {
            "fixed": "a16714e7cf2baa98ba2efddd5d6cbac641f4e76b"
          },
          {
            "fixed": "20383429b56974507c465d016e5238b189f7a246"
          },
          {
            "fixed": "7f57428ce00891d26b0f087ef754a4d820ec83aa"
          },
          {
            "fixed": "faea60deaa05c76f0772650f42eafde12bd39d93"
          },
          {
            "fixed": "07b71c342382b854ab8030b244aeab6a7228ad7d"
          },
          {
            "fixed": "4a69b83045d3195d5b9a9b053ad840ddb2998b4e"
          },
          {
            "fixed": "45ebb934ea50b436ce49b2f159f090dab0d7fa28"
          },
          {
            "fixed": "4d587cd8a72155089a627130bbd4716ec0856e21"
          }
        ]
      }
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63828.json"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "3.6.0"
          },
          {
            "fixed": "5.10.261"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "5.11.0"
          },
          {
            "fixed": "5.15.212"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "5.16.0"
          },
          {
            "fixed": "6.1.177"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.2.0"
          },
          {
            "fixed": "6.6.144"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.7.0"
          },
          {
            "fixed": "6.12.95"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.13.0"
          },
          {
            "fixed": "6.18.38"
          }
        ]
      },
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "6.19.0"
          },
          {
            "fixed": "7.1.3"
          }
        ]
      }
    ],
    "package": {
      "name": "Kernel",
      "ecosystem": "Linux"
    },
    "database_specific": {
      "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63828.json"
    }
  }
]
Related CVEs
CVE-2026-63828

Source reference: /id

Publisher severity

No explicit severity was provided.

Event
#50823 · Revision 1
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Publisher date
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