{"id":"CVE-2026-74682","title":"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->p…","summary":"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->p…","severity":"none","published":"2026-08-22","updated":"2026-10-14","sourceUpdated":"2026-10-14T13:10:00.187","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74682","references":[{"url":"https://git.kernel.org/stable/c/0a235379825e1a6194e43861ee6658e5fc35686d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/137bf034740e5a2734794908d0aff1e0bd7cee6e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6607f85242577f33d4540a0d1f4a6137f5367058","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/69ee44e1a23be62318189dc4b37fa4ad94053269","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6af5f29af7711233ae68d3b25c15d67478468900","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ca22c94bdfc22c564ca2e11c87ba4d17ebeaaa9a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d3ed4e6321bb453757044cb9e5ecb30a33f04903","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f1fbb50b99311b35c2e85cc70341d62082dca4b5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00177,"epssPercentile":0.06724,"ingestedAt":"2026-10-14T13:30:58.536Z","slug":"CVE-2026-74682","body":"## Overview\n\nIn 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>\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}