{"cve":"CVE-2026-63896","nvd":{"published":"2026-07-19T16:17:07.130","modified":"2026-07-27T17:44:23.777","status":"Awaiting Analysis","description":"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.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/046870ff6b6f7b743c953c061043a9b30700d491","https://git.kernel.org/stable/c/6c5dbc104dadd79fc2923497c20bae759a18758c","https://git.kernel.org/stable/c/a20f0ccf45708af6e063c7234c215d364b00de25","https://git.kernel.org/stable/c/f5869dfaa89854dcf34121036294d42d6c7acb8f","https://git.kernel.org/stable/c/f8f5a8f48c7cae3fac85e04b593bd47939f9725f"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:45:36.895656543+00:00"},"epss":{"cve":"CVE-2026-63896","score":0.00214,"percentile":0.11822,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}