GHSA-57GR-RX4P-H42M

Vulnerability from github – Published: 2026-07-29 09:31 – Updated: 2026-07-30 06:32
VLAI
Details

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

Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb()

l2cap_sock_new_connection_cb() returned l2cap_pi(sk)->chan after release_sock(parent). Once the parent lock is dropped the newly enqueued child socket sk is reachable via the accept queue, so another task can accept and free it before the callback dereferences sk, resulting in a use-after-free.

Rework the ->new_connection() op so the core, rather than the callback, owns the child channel's lifetime. The op now receives a pre-allocated new_chan and returns an errno instead of allocating and returning a channel. l2cap_new_connection() allocates the child channel and links it into the conn list via __l2cap_chan_add() before invoking the callback, so the conn-list reference keeps the channel alive once release_sock(parent) exposes the socket to other tasks.

Channel configuration that was duplicated in l2cap_sock_init() and the various new_connection callbacks is consolidated into l2cap_chan_set_defaults(), which now inherits from the parent channel when one is supplied.

Severity
8.8 (High)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64557"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-29T09:16:30Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb()\n\nl2cap_sock_new_connection_cb() returned l2cap_pi(sk)-\u003echan after\nrelease_sock(parent). Once the parent lock is dropped the newly\nenqueued child socket sk is reachable via the accept queue, so another\ntask can accept and free it before the callback dereferences sk,\nresulting in a use-after-free.\n\nRework the -\u003enew_connection() op so the core, rather than the callback,\nowns the child channel\u0027s lifetime. The op now receives a pre-allocated\nnew_chan and returns an errno instead of allocating and returning a\nchannel. l2cap_new_connection() allocates the child channel and links\nit into the conn list via __l2cap_chan_add() before invoking the\ncallback, so the conn-list reference keeps the channel alive once\nrelease_sock(parent) exposes the socket to other tasks.\n\nChannel configuration that was duplicated in l2cap_sock_init() and the\nvarious new_connection callbacks is consolidated into\nl2cap_chan_set_defaults(), which now inherits from the parent channel\nwhen one is supplied.",
  "id": "GHSA-57gr-rx4p-h42m",
  "modified": "2026-07-30T06:32:35Z",
  "published": "2026-07-29T09:31:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64557"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/36da806f7fbaee56ad9e81859deec203f9728700"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6fef032af0092ed5ccb767239a9ac1bc38c08a40"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/733e76e74e406c1d1ddc7369420dd8a47f48bb8a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/84e718b6a814edc84159361f9f454a4e92ae91ae"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8c37e4338c801ebb8cee52436c01c41e009f6e87"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b39298044e5534612511a2ff5de03ba5f6e7a820"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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