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CVE-2026-63896

Estado: Pendiente de análisisSin puntuar—

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

usb: gadget: composite: fix integer underflow in WebUSB GET_URL handling

The WebUSB GET_URL handler in composite_setup() narrows landing_page_length to fit the host-supplied wLength using

If wLength is smaller than WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH the unsigned subtraction wraps, and the subsequent

ends up copying close to UINT_MAX bytes from cdev->landing_page into cdev->req->buf. KASAN reports a slab-out-of-bounds in composite_setup on the kmalloc-2k gadget_info allocation, and FORTIFY_SOURCE traps the memcpy as a 4294967293-byte field-spanning write into url_descriptor->URL (size 252).

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A USB host can reach this from a single SETUP packet against any gadget that has webusb/use=1 and a landingPage configured.

Handle the small-wLength case before the math: when the host requested fewer bytes than the URL descriptor header, only the header is meaningful and no URL bytes need to be copied. Setting landing_page_length to landing_page_offset makes the existing memcpy a no-op and leaves the descriptor returned to the host unchanged for all larger wLength values.

Detalles técnicos trazas, registros y código del informe original
	landing_page_length = w_length
		- WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH + landing_page_offset;

	memcpy(url_descriptor->URL,
	       cdev->landing_page + landing_page_offset,
	       landing_page_length - landing_page_offset);

CVSS

NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).

Probabilidad de explotación (EPSS)

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).

Tecnologías afectadas (1)

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

Linux — Linux KernelAI

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-63896",
  "cveTags": [],
  "metrics": {},
  "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": [
            {
              "status": "affected",
              "version": "93c473948c588978cd55d9a3adad8b3e8057aa21",
              "lessThan": "046870ff6b6f7b743c953c061043a9b30700d491",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "93c473948c588978cd55d9a3adad8b3e8057aa21",
              "lessThan": "f5869dfaa89854dcf34121036294d42d6c7acb8f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "93c473948c588978cd55d9a3adad8b3e8057aa21",
              "lessThan": "f8f5a8f48c7cae3fac85e04b593bd47939f9725f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "93c473948c588978cd55d9a3adad8b3e8057aa21",
              "lessThan": "a20f0ccf45708af6e063c7234c215d364b00de25",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "93c473948c588978cd55d9a3adad8b3e8057aa21",
              "lessThan": "6c5dbc104dadd79fc2923497c20bae759a18758c",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "drivers/usb/gadget/composite.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.3"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.3",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver",
              "lessThanOrEqual": "7.0.*"
            },
            {
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "drivers/usb/gadget/composite.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-07-19T16:17:07.130",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/046870ff6b6f7b743c953c061043a9b30700d491",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6c5dbc104dadd79fc2923497c20bae759a18758c",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a20f0ccf45708af6e063c7234c215d364b00de25",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f5869dfaa89854dcf34121036294d42d6c7acb8f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f8f5a8f48c7cae3fac85e04b593bd47939f9725f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Awaiting Analysis",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: composite: fix integer underflow in WebUSB GET_URL handling\n\nThe WebUSB GET_URL handler in composite_setup() narrows\nlanding_page_length to fit the host-supplied wLength using\n\n\tlanding_page_length = w_length\n\t\t- WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH + landing_page_offset;\n\nIf wLength is smaller than WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH the\nunsigned subtraction wraps, and the subsequent\n\n\tmemcpy(url_descriptor->URL,\n\t       cdev->landing_page + landing_page_offset,\n\t       landing_page_length - landing_page_offset);\n\nends up copying close to UINT_MAX bytes from cdev->landing_page into\ncdev->req->buf.  KASAN reports a slab-out-of-bounds in composite_setup\non the kmalloc-2k gadget_info allocation, and FORTIFY_SOURCE traps the\nmemcpy as a 4294967293-byte field-spanning write into\nurl_descriptor->URL (size 252).\n\nA USB host can reach this from a single SETUP packet against any\ngadget that has webusb/use=1 and a landingPage configured.\n\nHandle the small-wLength case before the math: when the host requested\nfewer bytes than the URL descriptor header, only the header is\nmeaningful and no URL bytes need to be copied.  Setting\nlanding_page_length to landing_page_offset makes the existing memcpy a\nno-op and leaves the descriptor returned to the host unchanged for all\nlarger wLength values."
    }
  ],
  "lastModified": "2026-07-27T17:44:23.777",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}