GHSA-5HVQ-FG66-PRGG
Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-19 18:31In 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.
{
"affected": [],
"aliases": [
"CVE-2026-63896"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-19T16:17:07Z",
"severity": null
},
"details": "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-\u003eURL,\n\t cdev-\u003elanding_page + landing_page_offset,\n\t landing_page_length - landing_page_offset);\n\nends up copying close to UINT_MAX bytes from cdev-\u003elanding_page into\ncdev-\u003ereq-\u003ebuf. 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-\u003eURL (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.",
"id": "GHSA-5hvq-fg66-prgg",
"modified": "2026-07-19T18:31:44Z",
"published": "2026-07-19T18:31:44Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63896"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/046870ff6b6f7b743c953c061043a9b30700d491"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6c5dbc104dadd79fc2923497c20bae759a18758c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a20f0ccf45708af6e063c7234c215d364b00de25"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f5869dfaa89854dcf34121036294d42d6c7acb8f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f8f5a8f48c7cae3fac85e04b593bd47939f9725f"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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