CVE-2026-74682 (GCVE-0-2026-74682)
Vulnerability from cvelistv5
Published
2026-08-22 15:32
Modified
2026-08-22 15:32
Severity ?
VLAI Severity ?
EPSS score ?
Summary
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>
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 8fdff6a319e7dac757c558bd283dc4577e68cde7 Version: 8fdff6a319e7dac757c558bd283dc4577e68cde7 Version: 8fdff6a319e7dac757c558bd283dc4577e68cde7 Version: 8fdff6a319e7dac757c558bd283dc4577e68cde7 Version: 8fdff6a319e7dac757c558bd283dc4577e68cde7 Version: 8fdff6a319e7dac757c558bd283dc4577e68cde7 Version: 8fdff6a319e7dac757c558bd283dc4577e68cde7 Version: 8fdff6a319e7dac757c558bd283dc4577e68cde7 |
||
{
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"version": "0",
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},
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},
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"status": "unaffected",
"version": "5.15.216",
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},
{
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"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
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"version": "6.6.152",
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{
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{
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{
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"version": "7.1.9",
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},
{
"lessThanOrEqual": "*",
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}
]
}
],
"cpeApplicability": [
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"negate": false,
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],
"descriptions": [
{
"lang": "en",
"value": "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-\u003epackets = urb_packs;\n\tu-\u003ebuffer_size = maxsize * u-\u003epackets;\n\n\tif (fmt-\u003efmt_type == UAC_FORMAT_TYPE_II)\n\t\tu-\u003epackets++; /* for transfer delimiter */\n\tu-\u003eurb = usb_alloc_urb(u-\u003epackets, 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 \u003c urb_ctx-\u003epackets; i++) {\n\t\turb-\u003eiso_frame_desc[i].offset = offs;\n\t\turb-\u003eiso_frame_desc[i].length = ep-\u003ecurpacksize;\n\t\toffs += ep-\u003ecurpacksize;\n\t}\n\n\turb-\u003etransfer_buffer_length = offs;\n\turb-\u003enumber_of_packets = urb_ctx-\u003epackets;\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-\u003ebuffer_size, so only capture is affected.\n\nfmt_type comes from the device\u0027s 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 \u003cbaul.lee@xbow.com\u003e"
}
],
"providerMetadata": {
"dateUpdated": "2026-08-22T15:32:49.527Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/6af5f29af7711233ae68d3b25c15d67478468900"
},
{
"url": "https://git.kernel.org/stable/c/f1fbb50b99311b35c2e85cc70341d62082dca4b5"
},
{
"url": "https://git.kernel.org/stable/c/137bf034740e5a2734794908d0aff1e0bd7cee6e"
},
{
"url": "https://git.kernel.org/stable/c/6607f85242577f33d4540a0d1f4a6137f5367058"
},
{
"url": "https://git.kernel.org/stable/c/ca22c94bdfc22c564ca2e11c87ba4d17ebeaaa9a"
},
{
"url": "https://git.kernel.org/stable/c/0a235379825e1a6194e43861ee6658e5fc35686d"
},
{
"url": "https://git.kernel.org/stable/c/d3ed4e6321bb453757044cb9e5ecb30a33f04903"
},
{
"url": "https://git.kernel.org/stable/c/69ee44e1a23be62318189dc4b37fa4ad94053269"
}
],
"title": "ALSA: usb-audio: fix OOB write on Type II inbound URBs",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74682",
"datePublished": "2026-08-22T15:32:49.527Z",
"dateReserved": "2026-08-15T05:44:03.925Z",
"dateUpdated": "2026-08-22T15:32:49.527Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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