{"cve":"CVE-2026-74682","nvd":{"published":"2026-08-22T16:16:42.480","modified":"2026-10-14T13:10:00.187","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: usb-audio: fix OOB write on Type II inbound URBs\n\ndata_ep_set_params() sizes each URB transfer buffer before it adds the\nFormat Type II transfer delimiter:\n\n\tu->packets = urb_packs;\n\tu->buffer_size = maxsize * u->packets;\n\n\tif (fmt->fmt_type == UAC_FORMAT_TYPE_II)\n\t\tu->packets++; /* for transfer delimiter */\n\tu->urb = usb_alloc_urb(u->packets, GFP_KERNEL);\n\nbuffer_size is computed from the pre-increment packet count and never\nrecomputed, so for a Type II endpoint the buffer is one packet short of\nthe packet count the URB is built with.\n\nprepare_inbound_urb() then lays out one iso frame per packet and never\nconsults buffer_size:\n\n\toffs = 0;\n\tfor (i = 0; i < urb_ctx->packets; i++) {\n\t\turb->iso_frame_desc[i].offset = offs;\n\t\turb->iso_frame_desc[i].length = ep->curpacksize;\n\t\toffs += ep->curpacksize;\n\t}\n\n\turb->transfer_buffer_length = offs;\n\turb->number_of_packets = urb_ctx->packets;\n\nThe last descriptor therefore points one packet past the end of the\ntransfer buffer, where the host controller writes device data on every\ninbound transfer.  prepare_silent_urb() and prepare_playback_urb() bound\ntheir fill loops by ctx->buffer_size, so only capture is affected.\n\nfmt_type comes from the device's audio streaming descriptors, so any\ndevice advertising a Type II capture format hits this once userspace sets\nhw_params on the stream.\n\nKASAN on 7.2.0-rc5 (arm64) with a dummy_hcd/raw-gadget device, one report\nper inbound transfer:\n\n  BUG: KASAN: slab-out-of-bounds in dummy_timer\n  Write of size 64 at addr ffff0000186171c0 by task cons02/166\n   __asan_memcpy\n   dummy_timer\n   hrtimer_run_softirq\n  Allocated by task 166:\n   usb_alloc_coherent\n   snd_usb_endpoint_set_params\n  The buggy address is located 0 bytes to the right of\n   allocated 64-byte region [ffff000018617180, ffff0000186171c0)\n\nCompute buffer_size after the delimiter packet has been accounted for,\nand bound the fill loop by buffer_size, as prepare_silent_urb() already\ndoes on the outbound side.  This grows every Type II URB allocation by\none maxsize packet.\n\nDiscovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/0a235379825e1a6194e43861ee6658e5fc35686d","https://git.kernel.org/stable/c/137bf034740e5a2734794908d0aff1e0bd7cee6e","https://git.kernel.org/stable/c/6607f85242577f33d4540a0d1f4a6137f5367058","https://git.kernel.org/stable/c/69ee44e1a23be62318189dc4b37fa4ad94053269","https://git.kernel.org/stable/c/6af5f29af7711233ae68d3b25c15d67478468900"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:49:38.260478770+00:00"},"epss":{"cve":"CVE-2026-74682","score":0.00177,"percentile":0.07165,"date":"2026-10-25"},"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."]}