{"apiVersion":"1.0","identifier":"CVE-2026-74682","description":"In the Linux kernel, the following vulnerability has been resolved: ALSA: usb-audio: fix OOB write on Type II inbound URBs data_ep_set_params() sizes each URB transfer buffer before it adds the Format Type II transfer delimiter: u->packets = urb_packs; u->buffer_size = maxsize * u->packets; if (fmt->fmt_type == UAC_FORMAT_TYPE_II) u->packets++; /* for transfer delimiter */ u->urb = usb_alloc_urb(u->packets, GFP_KERNEL); buffer_size is computed from the pre-increment packet count and never recomputed, so for a Type II endpoint the buffer is one packet short of the packet count the URB is built with. prepare_inbound_urb() then lays out one iso frame per packet and never consults buffer_size: offs = 0; for (i = 0; i < urb_ctx->packets; i++) { urb->iso_frame_desc[i].offset = offs; urb->iso_frame_desc[i].length = ep->curpacksize; offs += ep->curpacksize; } urb->transfer_buffer_length = offs; urb->number_of_packets = urb_ctx->packets; The last descriptor therefore points one packet past the end of the transfer buffer, where the host controller writes device data on every inbound transfer. prepare_silent_urb() and prepare_playback_urb() bound their fill loops by ctx->buffer_size, so only capture is affected. fmt_type comes from the device-s audio streaming descriptors, so any device advertising a Type II capture format hits this once userspace sets hw_params on the stream. KASAN on 7.2.0-rc5 (arm64) with a dummy_hcd/raw-gadget device, one report per inbound transfer: BUG: KASAN: slab-out-of-bounds in dummy_timer Write of size 64 at addr ffff0000186171c0 by task cons02/166 __asan_memcpy dummy_timer hrtimer_run_softirq Allocated by task 166: usb_alloc_coherent snd_usb_endpoint_set_params The buggy address is located 0 bytes to the right of allocated 64-byte region [ffff000018617180, ffff0000186171c0) Compute buffer_size after the delimiter packet has been accounted for, and bound the fill loop by buffer_size, as prepare_silent_urb() already does on the outbound side. This grows every Type II URB allocation by one maxsize packet. Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>","publishedAt":"2026-08-22T16:16:42","lastModifiedAt":"2026-08-22T16:16:42","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74682","cvssScore":null,"cvssVector":"Pending","epssProbability":0.00177,"riskScore":0,"affectedProduct":"linux","affectedVersions":"unknown","vulnerabilityType":"Kernel","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-74682","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-74682","en":"https://www.redsauce.net/en/cves/CVE-2026-74682","fr":"https://www.redsauce.net/fr/cves/CVE-2026-74682","pt":"https://www.redsauce.net/pt/cves/CVE-2026-74682","de":"https://www.redsauce.net/de/cves/CVE-2026-74682","sk":"https://www.redsauce.net/sk/cves/CVE-2026-74682","el":"https://www.redsauce.net/el/cves/CVE-2026-74682"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-74682"}}