CVE-2026-74641

Estado: RecibidaAlta (7.8)—

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

ALSA: usx2y: bound the hwdep mmap fault offset

snd_us428ctls_vm_fault() turns the faulting page offset into a kernel address with no bound of any kind:

snd_us428ctls_mmap() checks only the length of the mapping, never the offset, and us428ctls_sharedmem is a single page from alloc_pages_exact(). For a character device file_mmap_size_max() returns ULONG_MAX, so the mm layer imposes no ceiling either. Every page offset above zero resolves to a struct page outside the object, and the handler installs it into the caller's address space read-write; the vma is not marked read-only.

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The caller picks the page frame with a single mmap() argument and gets read-write access to a page of kernel memory it does not own; an offset that lands in an unpopulated vmemmap region oopses instead.

A process that can open the hwdep node of an attached US-X2Y reaches this after loading the FPGA image through the same node; no capability check is involved.

On 7.2.0-rc5 (arm64), mmap() with a large offset:

Reject any offset outside the shared region. The pcm hwdep handler in usx2yhwdeppcm.c computes its address the same way and needs the same bound.

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

Detalles técnicos trazas, registros y código del informe original

	offset = vmf->pgoff << PAGE_SHIFT;
	vaddr = (char *)(...)->us428ctls_sharedmem + offset;
	page = virt_to_page(vaddr);
	get_page(page);
	vmf->page = page;

	return 0;

  Unable to handle kernel paging request at virtual address fffffdffc45d5ac8
  pc : snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
  Call trace:
   snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
   __do_fault
   __handle_mm_fault
   handle_mm_fault
   el0_da

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: 0.18%
Percentil entre todas las CVEs puntuadas: 6
Fecha de la puntuación: 6/10/2026

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 escalation90 %
Impacto principalT1005 Data from Local Systemcollection75 %
Impacto secundarioT1499.004 Application or System Exploitationimpact70 %

Vulnerabilidad de acceso local sin interacción (AV:L, PR:L, UI:N) con permisos elevados: lectura/escritura de memoria del kernel mediante mmap sin validación de offset. Causa acceso a páginas de kernel no propias (C:H, I:H) o negación de servicio (A:H).

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

Threat Intelligence Program Filter Network Traffic Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software

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-2026-74641",
  "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"
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          "programFiles": [
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              "version": "6.18.45",
              "versionType": "semver",
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          ],
          "programFiles": [
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            "sound/usb/usx2y/usx2yhwdeppcm.c"
          ],
          "defaultStatus": "affected"
        }
      ]
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  "published": "2026-08-22T16:16:37.383",
  "references": [
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      "url": "https://git.kernel.org/stable/c/10a87401fb3148c388e55df0148295b3b137da07",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: usx2y: bound the hwdep mmap fault offset\n\nsnd_us428ctls_vm_fault() turns the faulting page offset into a kernel\naddress with no bound of any kind:\n\n\toffset = vmf->pgoff << PAGE_SHIFT;\n\tvaddr = (char *)(...)->us428ctls_sharedmem + offset;\n\tpage = virt_to_page(vaddr);\n\tget_page(page);\n\tvmf->page = page;\n\n\treturn 0;\n\nsnd_us428ctls_mmap() checks only the length of the mapping, never the\noffset, and us428ctls_sharedmem is a single page from\nalloc_pages_exact().  For a character device file_mmap_size_max()\nreturns ULONG_MAX, so the mm layer imposes no ceiling either.  Every page\noffset above zero resolves to a struct page outside the object, and the\nhandler installs it into the caller's address space read-write; the vma\nis not marked read-only.\n\nThe caller picks the page frame with a single mmap() argument and gets\nread-write access to a page of kernel memory it does not own; an offset\nthat lands in an unpopulated vmemmap region oopses instead.\n\nA process that can open the hwdep node of an attached US-X2Y reaches\nthis after loading the FPGA image through the same node; no capability\ncheck is involved.\n\nOn 7.2.0-rc5 (arm64), mmap() with a large offset:\n\n  Unable to handle kernel paging request at virtual address fffffdffc45d5ac8\n  pc : snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]\n  Call trace:\n   snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]\n   __do_fault\n   __handle_mm_fault\n   handle_mm_fault\n   el0_da\n\nReject any offset outside the shared region.  The pcm hwdep handler in\nusx2yhwdeppcm.c computes its address the same way and needs the same\nbound.\n\nDiscovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>"
    }
  ],
  "lastModified": "2026-08-25T06:18:43.980",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}