GHSA-GGW5-JW3C-R95V

Vulnerability from github – Published: 2026-04-03 18:31 – Updated: 2026-04-27 15:30
VLAI
Details

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

Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user

After commit ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del"), l2cap_conn_del() uses conn->lock to protect access to conn->users. However, l2cap_register_user() and l2cap_unregister_user() don't use conn->lock, creating a race condition where these functions can access conn->users and conn->hchan concurrently with l2cap_conn_del().

This can lead to use-after-free and list corruption bugs, as reported by syzbot.

Fix this by changing l2cap_register_user() and l2cap_unregister_user() to use conn->lock instead of hci_dev_lock(), ensuring consistent locking for the l2cap_conn structure.

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-2026-23461"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-362",
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-03T16:16:33Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user\n\nAfter commit ab4eedb790ca (\"Bluetooth: L2CAP: Fix corrupted list in\nhci_chan_del\"), l2cap_conn_del() uses conn-\u003elock to protect access to\nconn-\u003eusers. However, l2cap_register_user() and l2cap_unregister_user()\ndon\u0027t use conn-\u003elock, creating a race condition where these functions can\naccess conn-\u003eusers and conn-\u003ehchan concurrently with l2cap_conn_del().\n\nThis can lead to use-after-free and list corruption bugs, as reported\nby syzbot.\n\nFix this by changing l2cap_register_user() and l2cap_unregister_user()\nto use conn-\u003elock instead of hci_dev_lock(), ensuring consistent locking\nfor the l2cap_conn structure.",
  "id": "GHSA-ggw5-jw3c-r95v",
  "modified": "2026-04-27T15:30:31Z",
  "published": "2026-04-03T18:31:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23461"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/11a87dd5df428a4b79a84d2790cac7f3c73f1f0d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/71030f3b3015a412133a805ff47970cdcf30c2b8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/752a6c9596dd25efd6978a73ff21f3b592668f4a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c22a5e659959eb77c2fbb58a5adfaf3c3dab7abf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/da3000cbe4851458a22be38bb18c0689c39fdd5f"
    }
  ],
  "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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