CVE-2026-74268 (GCVE-0-2026-74268)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:57 – Updated: 2026-08-17 05:45
VLAI
Title
tcp: clear sock_ops cb flags before force-closing a child socket
Summary
In the Linux kernel, the following vulnerability has been resolved: tcp: clear sock_ops cb flags before force-closing a child socket A child socket inherits the listener's bpf_sock_ops_cb_flags via sk_clone_lock(). If its setup fails in tcp_v4_syn_recv_sock() / tcp_v6_syn_recv_sock(), the child is freed through put_and_exit, where inet_csk_prepare_forced_close() drops the socket lock and tcp_done() runs without it. If BPF_SOCK_OPS_STATE_CB_FLAG was inherited, tcp_done() -> tcp_set_state() calls tcp_call_bpf(), which expects the lock and trips sock_owned_by_me(): WARNING: include/net/sock.h:1799 at tcp_set_state+0x433/0x550 RIP: 0010:tcp_set_state+0x433/0x550 include/net/sock.h:1799 Call Trace: <IRQ> tcp_done+0xba/0x250 net/ipv4/tcp.c:5095 tcp_v4_syn_recv_sock+0x850/0xa50 net/ipv4/tcp_ipv4.c:1787 tcp_check_req+0xf30/0x1360 net/ipv4/tcp_minisocks.c:926 tcp_v4_rcv+0x1047/0x1b50 net/ipv4/tcp_ipv4.c:2164 </IRQ> The child is freed before it is ever established, so it should run no sock_ops callback. Clear its cb flags in inet_csk_prepare_for_destroy_sock(), the common point for the IPv4, IPv6 and chtls forced-close paths and for the MPTCP ->syn_recv_sock() failure path (dispose_child), which reaches tcp_done() on a child that was never established too.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: d44874910a26f3a8f81edf873a2473363f07f660 , < ce311bd2e36596f0aa2c92ca86fb3e019ac57eae (git)
Affected: d44874910a26f3a8f81edf873a2473363f07f660 , < 8874dafc9099bc49c2e5ebba030f85d276421f92 (git)
Affected: d44874910a26f3a8f81edf873a2473363f07f660 , < 990348e5bb457697c2f1f7f7b65154a3334d9d2b (git)
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Linux Linux Affected: 4.16
Unaffected: 0 , < 4.16 (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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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/tcp.h",
            "net/ipv4/inet_connection_sock.c"
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          "vendor": "Linux",
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              "operator": "OR"
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: clear sock_ops cb flags before force-closing a child socket\n\nA child socket inherits the listener\u0027s bpf_sock_ops_cb_flags via\nsk_clone_lock(). If its setup fails in tcp_v4_syn_recv_sock() /\ntcp_v6_syn_recv_sock(), the child is freed through put_and_exit, where\ninet_csk_prepare_forced_close() drops the socket lock and tcp_done() runs\nwithout it.\n\nIf BPF_SOCK_OPS_STATE_CB_FLAG was inherited, tcp_done() -\u003e tcp_set_state()\ncalls tcp_call_bpf(), which expects the lock and trips sock_owned_by_me():\n\n  WARNING: include/net/sock.h:1799 at tcp_set_state+0x433/0x550\n  RIP: 0010:tcp_set_state+0x433/0x550 include/net/sock.h:1799\n  Call Trace:\n   \u003cIRQ\u003e\n   tcp_done+0xba/0x250 net/ipv4/tcp.c:5095\n   tcp_v4_syn_recv_sock+0x850/0xa50 net/ipv4/tcp_ipv4.c:1787\n   tcp_check_req+0xf30/0x1360 net/ipv4/tcp_minisocks.c:926\n   tcp_v4_rcv+0x1047/0x1b50 net/ipv4/tcp_ipv4.c:2164\n   \u003c/IRQ\u003e\n\nThe child is freed before it is ever established, so it should run no\nsock_ops callback. Clear its cb flags in inet_csk_prepare_for_destroy_sock(),\nthe common point for the IPv4, IPv6 and chtls forced-close paths and for the\nMPTCP -\u003esyn_recv_sock() failure path (dispose_child), which reaches tcp_done()\non a child that was never established too."
        }
      ],
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
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              "value": "AV:N - Remote attackers reach inet_csk_prepare_for_forced_close() via the standard TCP input path (tcp_v4_rcv/tcp_v6_rcv \u2192 tcp_check_req \u2192 tcp_v4/v6_syn_recv_sock put_and_exit) while processing attacker-sent handshake packets in softirq, with no local access required.\nAC:L - Attackers control handshake completion and can repeatedly force child setup failures\u2014e.g., MPTCP JOIN/sport-mismatch dispose_child paths, ENOMEM under connection pressure in __inet_inherit_port or MD5/AO copy, or chtls setup failure\u2014making put_and_exit reachable without conditions outside their influence.\nPR:N - The receive path is pre-authentication TCP/MPTCP processing; no victim credentials or capabilities are required. Exploitation only needs network reachability to a listener whose admin already attached cgroup BPF sock_ops setting BPF_SOCK_OPS_STATE_CB_FLAG (common on Kubernetes/Cilium/cloud nodes).\nUI:N - No victim interaction is needed beyond normal exposure of a TCP listener; the attacker triggers the bug entirely by sending network packets that complete then fail child socket creation.\nS:U - Vulnerability impact stays within the kernel on the host receiving the traffic; it does not cross VM, container runtime, or IOMMU security boundaries and represents standard in-kernel memory/lock safety impact.\nC:H - Inherited BPF_SOCK_OPS_STATE_CB_FLAG causes tcp_call_bpf() to run on an unlocked, partially torn-down child socket; BPF helpers can read tcp_sock fields without proper locking, enabling unsynchronized kernel memory reads that could disclose sensitive data.\nI:H - tcp_call_bpf() marks is_locked_tcp_sock while the socket lock was dropped, allowing cgroup BPF sock_ops programs to call bpf_setsockopt and modify tcp_sock/kernel state during forced close, creating plausible memory corruption and control-flow compromise primitives.\nA:H - sock_owned_by_me() WARN fires on this path and concurrent BPF access during tcp_done()/inet_csk_destroy_sock() can cause kernel oops or panic; remote attackers can repeatedly trigger the softirq failure path for denial of service on internet-facing BPF-enabled servers."
            }
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      ],
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        "dateUpdated": "2026-08-17T05:45:14.504Z",
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/990348e5bb457697c2f1f7f7b65154a3334d9d2b"
        }
      ],
      "title": "tcp: clear sock_ops cb flags before force-closing a child socket",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74268",
    "datePublished": "2026-08-15T05:57:42.920Z",
    "dateReserved": "2026-08-15T05:44:03.878Z",
    "dateUpdated": "2026-08-17T05:45:14.504Z",
    "state": "PUBLISHED"
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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.

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  • 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.
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  • 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.


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