GHSA-XRW5-G7CV-C5P3

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-19 18:32
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

net/packet: avoid fanout hook re-registration after unregister

packet_set_ring() temporarily detaches a socket from packet delivery while reconfiguring its ring. It records the previous running state, clears po->num, unregisters the protocol hook when needed, drops po->bind_lock, and later restores po->num and re-registers the hook from the saved was_running value.

That unlocked window can race with NETDEV_UNREGISTER. The notifier can observe the socket as not running, skip __unregister_prot_hook(), and invalidate the per-socket binding by setting po->ifindex to -1 and clearing po->prot_hook.dev. A one-member fanout group can still retain its shared fanout hook device pointer. When packet_set_ring() resumes, re-registering solely from the stale was_running state can re-add the fanout hook after the device has been unregistered.

Treat po->ifindex == -1 as an invalidated binding after reacquiring po->bind_lock. This is distinct from ifindex 0, the normal unbound/wildcard state: ifindex -1 marks an existing device binding that was invalidated when the device was unregistered. Restore po->num as before, but do not re-register the hook if device unregister already detached the socket.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-68338"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:20:24Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/packet: avoid fanout hook re-registration after unregister\n\npacket_set_ring() temporarily detaches a socket from packet delivery while\nreconfiguring its ring. It records the previous running state, clears\npo-\u003enum, unregisters the protocol hook when needed, drops po-\u003ebind_lock,\nand later restores po-\u003enum and re-registers the hook from the saved\nwas_running value.\n\nThat unlocked window can race with NETDEV_UNREGISTER. The notifier can\nobserve the socket as not running, skip __unregister_prot_hook(), and\ninvalidate the per-socket binding by setting po-\u003eifindex to -1 and clearing\npo-\u003eprot_hook.dev. A one-member fanout group can still retain its shared\nfanout hook device pointer. When packet_set_ring() resumes, re-registering\nsolely from the stale was_running state can re-add the fanout hook after\nthe device has been unregistered.\n\nTreat po-\u003eifindex == -1 as an invalidated binding after reacquiring\npo-\u003ebind_lock. This is distinct from ifindex 0, the normal\nunbound/wildcard state: ifindex -1 marks an existing device binding that\nwas invalidated when the device was unregistered. Restore po-\u003enum as\nbefore, but do not re-register the hook if device unregister already\ndetached the socket.",
  "id": "GHSA-xrw5-g7cv-c5p3",
  "modified": "2026-08-19T18:32:15Z",
  "published": "2026-08-10T15:33:46Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68338"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0a052e0808e015e68144a9877e6ef42b952c49fa"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1bc55c29cd85818e9052f17deb287d5a11fb817f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4628efbdc7affd094181f5263e65c1062e31f15f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/50aff80475abd3533eef4320477037e6fcc6b56e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/80ec024d53a05c60ad1d08968dcf745f10c1665c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a885387dae7986a55bae5c77a15bdd447f64e9b9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/acb40ebfa5c4d62f84339fcbf713f2a9fd033a71"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c820f4b7f2fa38f8769db0d0cefdd94e2721504d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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