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Out-of-bounds Write Affecting kernel-rt-64k-debug-modules package, versions *

Severity

 Recommended
medium

Based on CentOS security rating.

Threat Intelligence

EPSS
0.18% (8th percentile)

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  • Snyk IDSNYK-CENTOS10-KERNELRT64KDEBUGMODULES-19251064
  • published25 Aug 2026
  • disclosed22 Aug 2026
Report a new vulnerability Found a mistake?

Introduced: 22 Aug 2026

NewCVE-2026-74682  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-rt-64k-debug-modules.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-debug-modules package and not the kernel-rt-64k-debug-modules package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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>

CVSS Base Scores

version 3.1