{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.94-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.0.12-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "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  \tlanding_page_length = w_length \t\t- WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH + landing_page_offset;  If wLength is smaller than WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH the unsigned subtraction wraps, and the subsequent  \tmemcpy(url_descriptor-\u003eURL, \t       cdev-\u003elanding_page + landing_page_offset, \t       landing_page_length - landing_page_offset);  ends up copying close to UINT_MAX bytes from cdev-\u003elanding_page into cdev-\u003ereq-\u003ebuf.  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-\u003eURL (size 252).  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.",
  "id": "DEBIAN-CVE-2026-63896",
  "modified": "2026-09-14T16:47:30.741203005Z",
  "published": "2026-07-19T16:17:07.130Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-63896"
    }
  ],
  "upstream": [
    "CVE-2026-63896"
  ]
}