Vulnerability-Lookup

GHSA-FVHV-V8P3-VRWQ

Vulnerability from github – Published: 2026-07-19 12:30 – Updated: 2026-07-20 15:31

Details

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.

Severity

8.4 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-63828"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T12:16:56Z",
    "severity": "HIGH"
  },
  "details": "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": "GHSA-fvhv-v8p3-vrwq",
  "modified": "2026-07-20T15:31:47Z",
  "published": "2026-07-19T12:30:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63828"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/07b71c342382b854ab8030b244aeab6a7228ad7d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/45ebb934ea50b436ce49b2f159f090dab0d7fa28"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4a69b83045d3195d5b9a9b053ad840ddb2998b4e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4d587cd8a72155089a627130bbd4716ec0856e21"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7f57428ce00891d26b0f087ef754a4d820ec83aa"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/faea60deaa05c76f0772650f42eafde12bd39d93"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-63828 (GCVE-0-2026-63828)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:02 – Updated: 2026-07-20 13:40

Title

apparmor: mediate the implicit connect of TCP fast open sendmsg

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.

Severity

8.4 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Assigner

Linux

References

6 references

URL	Tags
https://git.kernel.org/stable/c/7f57428ce00891d26…
https://git.kernel.org/stable/c/faea60deaa05c76f0…
https://git.kernel.org/stable/c/07b71c342382b854a…
https://git.kernel.org/stable/c/4a69b83045d3195d5…
https://git.kernel.org/stable/c/45ebb934ea50b436c…
https://git.kernel.org/stable/c/4d587cd8a72155089…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < 7f57428ce00891d26b0f087ef754a4d820ec83aa (git) Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < faea60deaa05c76f0772650f42eafde12bd39d93 (git) Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < 07b71c342382b854ab8030b244aeab6a7228ad7d (git) Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < 4a69b83045d3195d5b9a9b053ad840ddb2998b4e (git) Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < 45ebb934ea50b436ce49b2f159f090dab0d7fa28 (git) Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < 4d587cd8a72155089a627130bbd4716ec0856e21 (git)
Linux	Linux	Affected: 3.6 Unaffected: 0 , < 3.6 (semver) Unaffected: 6.1.177 , ≤ 6.1.* (semver) Unaffected: 6.6.144 , ≤ 6.6.* (semver) Unaffected: 6.12.95 , ≤ 6.12.* (semver) Unaffected: 6.18.38 , ≤ 6.18.* (semver) Unaffected: 7.1.3 , ≤ 7.1.* (semver) Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)

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              "status": "unaffected",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-FVHV-V8P3-VRWQ

CVE-2026-63828 (GCVE-0-2026-63828)

Tags

Sightings

Nomenclature