CVE-2026-80971

Estado: RecibidaAlta (7.8)—

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

ALSA: bcd2000: clear the URB pointers on disconnect

bcd2000_free_usb_related_resources() frees both URBs and leaves the pointers behind:

The rawmidi device outlives that call. A substream that is still open when the device is unplugged reaches bcd2000_midi_send() from the trigger path on close. That function writes to the freed URB and then hands it to the USB core:

usb_kill_urb() does not stop a later submission either, so a submit that races the disconnect can requeue the URB after it has been reaped. midi_in_urb is exposed the same way: bcd2000_input_complete() resubmits it from the completion handler.

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Clear both pointers after freeing and test them on the paths that can still run. Poison the URBs before freeing them: usb_poison_urb() waits for a running completion handler and rejects any later submission, so after it returns the input path is quiesced and only the rawmidi trigger path can still reach bcd2000_midi_send(). No unpoison is needed; the URBs are freed on the next line.

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

Detalles técnicos trazas, registros y código del informe original

	usb_kill_urb(bcd2k->midi_out_urb);
	usb_kill_urb(bcd2k->midi_in_urb);

	usb_free_urb(bcd2k->midi_out_urb);
	usb_free_urb(bcd2k->midi_in_urb);

	bcd2k->midi_out_urb->transfer_buffer_length = BUFSIZE;
	...
	ret = usb_submit_urb(bcd2k->midi_out_urb, GFP_ATOMIC);

KASAN on 7.2.0-rc5 (arm64):

  BUG: KASAN: slab-use-after-free in bcd2000_midi_send [snd_bcd2000]
  Write of size 4 at addr ffff00001827d388 by task bpoc/168
   __asan_store4
   bcd2000_midi_send [snd_bcd2000]
   bcd2000_midi_output_trigger [snd_bcd2000]
   snd_rawmidi_kernel_write1
   close_substream.part.0
  Freed by task 168:
   usb_free_urb
   bcd2000_disconnect [snd_bcd2000]

  BUG: KASAN: slab-use-after-free in usb_submit_urb
  Read of size 8 at addr ffff00001827d3b8 by task bpoc/168

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.16%
Percentil entre todas las CVEs puntuadas: 5
Fecha de la puntuación: 5/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation75 %
Impacto principalT1059 Command and Scripting Interpreterexecution65 %

Vulnerabilidad de use-after-free en kernel Linux (AV:L, PR:L) que permite ejecución de código local al escribir en memoria liberada mediante URB de ALSA tras desconexión de dispositivo USB.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Execution Prevention Threat Intelligence Program Restrict Web-Based Content Privileged Account Management Limit Software Installation Behavior Prevention on Endpoint

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-80971",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
    ]
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  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
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              "status": "affected",
              "version": "b47a22290d581277be70e8a597824a4985d39e83",
              "lessThan": "9af08677aa57debaca5b57c8045c52a83d3dd376",
              "versionType": "git"
            },
            {
              "status": "affected",
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            {
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              "versionType": "git"
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            {
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              "versionType": "git"
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            {
              "status": "affected",
              "version": "b47a22290d581277be70e8a597824a4985d39e83",
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            {
              "status": "affected",
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              "versionType": "git"
            }
          ],
          "programFiles": [
            "sound/usb/bcd2000/bcd2000.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
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              "status": "affected",
              "version": "3.16"
            },
            {
              "status": "unaffected",
              "version": "0",
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            },
            {
              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "sound/usb/bcd2000/bcd2000.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:19:03.233",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/3c00004f134fc819f9d9e202c6a64acde0a1f8d0",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/459d3a64766f5ca2f1886daeaf24582831a5f5ab",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5a77febac6faf6da40fbb4555f703eeb91b58130",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/7df3194bdb7479cad9199889655a566a2c0c1d1b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9af08677aa57debaca5b57c8045c52a83d3dd376",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b06ebc7fe25a6af4a9f6e4a3d4236a4178ad4b01",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/eb482a06791d6168beb8c78cc904ac5a5ed96a55",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: bcd2000: clear the URB pointers on disconnect\n\nbcd2000_free_usb_related_resources() frees both URBs and leaves the\npointers behind:\n\n\tusb_kill_urb(bcd2k->midi_out_urb);\n\tusb_kill_urb(bcd2k->midi_in_urb);\n\n\tusb_free_urb(bcd2k->midi_out_urb);\n\tusb_free_urb(bcd2k->midi_in_urb);\n\nThe rawmidi device outlives that call.  A substream that is still open\nwhen the device is unplugged reaches bcd2000_midi_send() from the\ntrigger path on close.  That function writes to the freed URB and then\nhands it to the USB core:\n\n\tbcd2k->midi_out_urb->transfer_buffer_length = BUFSIZE;\n\t...\n\tret = usb_submit_urb(bcd2k->midi_out_urb, GFP_ATOMIC);\n\nusb_kill_urb() does not stop a later submission either, so a submit that\nraces the disconnect can requeue the URB after it has been reaped.\nmidi_in_urb is exposed the same way: bcd2000_input_complete() resubmits\nit from the completion handler.\n\nKASAN on 7.2.0-rc5 (arm64):\n\n  BUG: KASAN: slab-use-after-free in bcd2000_midi_send [snd_bcd2000]\n  Write of size 4 at addr ffff00001827d388 by task bpoc/168\n   __asan_store4\n   bcd2000_midi_send [snd_bcd2000]\n   bcd2000_midi_output_trigger [snd_bcd2000]\n   snd_rawmidi_kernel_write1\n   close_substream.part.0\n  Freed by task 168:\n   usb_free_urb\n   bcd2000_disconnect [snd_bcd2000]\n\n  BUG: KASAN: slab-use-after-free in usb_submit_urb\n  Read of size 8 at addr ffff00001827d3b8 by task bpoc/168\n\nClear both pointers after freeing and test them on the paths that can\nstill run.  Poison the URBs before freeing them: usb_poison_urb() waits\nfor a running completion handler and rejects any later submission, so\nafter it returns the input path is quiesced and only the rawmidi trigger\npath can still reach bcd2000_midi_send().  No unpoison is needed; the\nURBs are freed on the next line.\n\nDiscovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>"
    }
  ],
  "lastModified": "2026-09-14T13:18:51.890",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}