GHSA-5J9G-R9X8-9248

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33
VLAI
Details

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

can: isotp: use unconditional synchronize_rcu() in isotp_release()

isotp_notify() unregisters the (RCU) CAN filters via can_rx_unregister() and clears so->bound without waiting for a grace period. isotp_release() uses so->bound to decide whether it needs to call synchronize_rcu() before cancelling so->rxtimer, so when NETDEV_UNREGISTER runs first it skips that synchronize_rcu() and can cancel the timer while an in-flight isotp_rcv() is still executing and about to re-arm it via isotp_send_fc(), leading to a use-after-free timer callback on the freed socket.

sakisho-bot remarked a problem with rtnl_lock held in isotp_notify(), therefore make isotp_release() always call synchronize_rcu() before cancelling the timers, regardless of so->bound. This still closes the original race (isotp_notify() clearing so->bound without waiting for in-flight isotp_rcv() callers before isotp_release() cancels the RX timer) without adding any RCU wait to the netdevice notifier path.

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-2026-72126"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:21:29Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: isotp: use unconditional synchronize_rcu() in isotp_release()\n\nisotp_notify() unregisters the (RCU) CAN filters via can_rx_unregister()\nand clears so-\u003ebound without waiting for a grace period. isotp_release()\nuses so-\u003ebound to decide whether it needs to call synchronize_rcu()\nbefore cancelling so-\u003erxtimer, so when NETDEV_UNREGISTER runs first it\nskips that synchronize_rcu() and can cancel the timer while an\nin-flight isotp_rcv() is still executing and about to re-arm it via\nisotp_send_fc(), leading to a use-after-free timer callback on the\nfreed socket.\n\nsakisho-bot remarked a problem with rtnl_lock held in isotp_notify(),\ntherefore make isotp_release() always call synchronize_rcu() before\ncancelling the timers, regardless of so-\u003ebound. This still closes the\noriginal race (isotp_notify() clearing so-\u003ebound without waiting for\nin-flight isotp_rcv() callers before isotp_release() cancels the RX\ntimer) without adding any RCU wait to the netdevice notifier path.",
  "id": "GHSA-5j9g-r9x8-9248",
  "modified": "2026-08-17T06:33:11Z",
  "published": "2026-08-15T06:32:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72126"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/15413a082df69175c2f96aeab4c26fe1ff7cff03"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/59672aa4bcd8d32172c1ff6a179583981d6acabc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6280eda96e0707264849fa7d036fed873c1f8a6d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/945d9894502cd9124f5d676181c542ed2000f7c0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9b1a02e0d980ac6b0e36a90378f847062f81d7e4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b8278ff605187ef3fa0f2705e93251cce4c4f8ee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b88a511308779c225005d7994b8744561bdbafbc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb6abc584a1bfab107ac003d64948a4aef1730aa"
    }
  ],
  "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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