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CVE-2026-72243 (GCVE-0-2026-72243)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-18 06:56
VLAI
Title
selinux: check connect-related permissions on TCP Fast Open
Summary
In the Linux kernel, the following vulnerability has been resolved: selinux: check connect-related permissions on TCP Fast Open Similar to Landlock, SELinux was not updated when TCP Fast Open support was introduced to ensure connect-related permissions are checked when using TCP Fast Open. Update its socket_sendmsg() hook to call selinux_socket_connect() when MSG_FASTOPEN is passed.
Severity
8.4 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < 11406d0d7e11b4e525bb2ace2c70107031d058da (git)
Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < e507633bf76bccf1a6af27771fb0d6e2862b7eac (git)
Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < d028bc080a0dcd6a7f8e1ae1bd32dda696505ba3 (git)
Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < fc633a598206d4f23af782db7c0b5f3a82751d2c (git)
Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < 646ebbc5f2ff9147d084e1213143f091026a611c (git)
Affected: cf60af03ca4e71134206809ea892e49b92a88896 , < 44c74d27d1b9aaa99fa8a83640c1223575262b80 (git)
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Linux Linux Affected: 3.6
Unaffected: 0 , < 3.6 (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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        }
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              "value": "AV:L - Exploitation requires a confined local process to invoke sendmsg(2)/sendto(2) with MSG_FASTOPEN; the vulnerable selinux_socket_sendmsg() LSM hook runs on the syscall path before TCP fast-open performs its implicit connect.\nAC:L - A confined task with SOCKET__WRITE can reliably trigger the bypass with one sendmsg/sendto using MSG_FASTOPEN and a destination address; TFO client is enabled by default (sysctl_tcp_fastopen=TFO_CLIENT_ENABLE) and no race or special victim state is needed.\nPR:L - The attacker must be an unprivileged process in a SELinux domain that grants socket write but denies connect/name_connect (e.g., confined Android apps, container workloads, hardened service domains); no real root or init-namespace privileges are required.\nUI:N - No victim interaction is required; the confined attacker process directly issues the bypassing syscall without needing another user or administrator to perform any action.\nS:C - Successful exploitation crosses the SELinux MAC confinement boundary, allowing a sandboxed domain to establish outbound TCP/MPTCP connections that connect(2) and name_connect policy would have blocked, escaping the intended network policy scope.\nC:H - Bypassing connect and name_connect mediation lets a confined process open TCP/MPTCP sessions to SELinux-forbidden destinations and read arbitrary response data from those services (internal APIs, metadata endpoints, databases), constituting unauthorized information disclosure.\nI:H - The bypass enables unauthorized outbound connection establishment and transmission of arbitrary application data (including SYN-cookie payload) to hosts and ports explicitly denied by SELinux connect/name_connect rules, violating integrity of the confinement policy.\nA:N - This is a pure SELinux LSM policy-bypass flaw with no kernel memory corruption, panic, oops, hang, or resource exhaustion; exploitation does not impact system availability."
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      "cve": "CVE-2026-72243",
      "id": "CVE-2026-72243",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:fixed": "303",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: selinux: check connect-related permissions on TCP Fast Open",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72243.json",
      "version": "3"
    },
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      "current_release_date": "2026-09-19T01:50:13Z",
      "cve": "CVE-2026-72243",
      "id": "CVE-2026-72243",
      "initial_release_date": "2026-08-31T16:26:36Z",
      "product_status:known_affected": "82",
      "product_status:known_not_affected": "280",
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      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72243",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72243.json",
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    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.