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Vulnerability

CVE-2026-63896

Reference data from vuln.mlab.sh, coverage from our own index.

CVSS
7.0 High
Vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
0.21%
Risk score
8.2
Published
2026-07-19
Status
Published

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 landing_page_length = w_length - 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 memcpy(url_descriptor->URL, cdev->landing_page + landing_page_offset, landing_page_length - landing_page_offset); 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). 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. A flaw was found in the Linux kernel's USB gadget composite driver. A remote attacker, acting as a malicious USB host, could send a specially crafted `GET_URL` request. This request, with a small `wLength` value, triggers an integer underflow when calculating the buffer length for a memory copy operation. This leads to an out-of-bounds write, causing memory corruption and potentially a denial of service or arbitrary code execution.

Weaknesses

CWE-787

Coverage 5

Advisories and references