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GHSA-JC2G-JX97-4CG9

Vulnerability from github – Published: 2026-08-15 15:30 – Updated: 2026-08-15 15:30
VLAI
Details

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

ALSA: usb-audio: fix use-after-free in ump_to_endpoint()

create_midi2_ump() registers a card-owned snd_ump_endpoint and stores a back-pointer to its per-interface snd_usb_midi2_ump object in ump->private_data, but it never installs an ump->private_free hook and never clears that pointer.

If a later step of snd_usb_midi_v2_create() fails, its error path calls free_all_midi2_umps(), which kfree()s the snd_usb_midi2_ump object while the already-registered endpoint keeps pointing at it. The created /dev/snd/umpCD node stays exposed, so the first operation of any UMP open, ump_to_endpoint(), dereferences the dangling ump->private_data and reads rmidi->eps[dir] out of freed memory.

A malicious USB MIDI 2.0 device that makes creation fail after the endpoint is registered can thus trigger a slab use-after-free read on a subsequent open of the UMP node.

Clear the endpoint's back-pointer before freeing the object, and let ump_to_endpoint() tolerate a NULL private_data so the open/close/trigger callbacks fail cleanly (their callers already handle a NULL endpoint) instead of dereferencing a stale pointer.

Discovered by XBOW, triaged by Baul Lee baul.lee@xbow.com

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{
  "affected": [],
  "aliases": [
    "CVE-2026-74501"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T13:17:55Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: usb-audio: fix use-after-free in ump_to_endpoint()\n\ncreate_midi2_ump() registers a card-owned snd_ump_endpoint and stores a\nback-pointer to its per-interface snd_usb_midi2_ump object in\nump-\u003eprivate_data, but it never installs an ump-\u003eprivate_free hook and\nnever clears that pointer.\n\nIf a later step of snd_usb_midi_v2_create() fails, its error path calls\nfree_all_midi2_umps(), which kfree()s the snd_usb_midi2_ump object while\nthe already-registered endpoint keeps pointing at it.  The created\n/dev/snd/umpC*D* node stays exposed, so the first operation of any UMP\nopen, ump_to_endpoint(), dereferences the dangling ump-\u003eprivate_data and\nreads rmidi-\u003eeps[dir] out of freed memory.\n\nA malicious USB MIDI 2.0 device that makes creation fail after the\nendpoint is registered can thus trigger a slab use-after-free read on a\nsubsequent open of the UMP node.\n\nClear the endpoint\u0027s back-pointer before freeing the object, and let\nump_to_endpoint() tolerate a NULL private_data so the open/close/trigger\ncallbacks fail cleanly (their callers already handle a NULL endpoint)\ninstead of dereferencing a stale pointer.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e",
  "id": "GHSA-jc2g-jx97-4cg9",
  "modified": "2026-08-15T15:30:34Z",
  "published": "2026-08-15T15:30:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74501"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/49eccef6d6e1c00dac6fb2e7eb6f9206c33e1c37"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4a05b2d1b4642df74f30b6f54843e825c4a2bfd3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8a7a33b846d6ba695891b8d0040027cdbad8cd52"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ae388c0e1bf727972096f770f82d12e4f748d1b6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cc014ebf803174f0e5d15956dfc5a38413c945ae"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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