CVE-2026-74682
Full vulnerability record from the local CVENow database.
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 <[email protected]>
Severity
Not scored
CVSS score
Not available
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-08-22 16:16:42.480000
Last modified
2026-11-06 17:19:54.510000
View original CVE JSON
{
"id": "CVE-2026-74682",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-08-22T16:16:42.480",
"lastModified": "2026-11-06T17:19:54.510",
"vulnStatus": "Received",
"cveTags": [],
"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->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 <[email protected]>"
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nALSA: usb-audio: corrige escritura fuera de límites en URBs entrantes de Tipo II\n\ndata_ep_set_params() dimensiona cada búfer de transferencia URB antes de añadir el delimitador de transferencia de Formato Tipo II:\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 se calcula a partir del recuento de paquetes previo al incremento y nunca se vuelve a calcular, por lo que para un punto final de Tipo II el búfer tiene un paquete menos que el recuento de paquetes con el que se construye el URB.\n\nprepare_inbound_urb() luego organiza un marco iso por paquete y nunca consulta 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\nEl último descriptor, por lo tanto, apunta un paquete más allá del final del búfer de transferencia, donde el controlador de host escribe datos del dispositivo en cada transferencia entrante. prepare_silent_urb() y prepare_playback_urb() limitan sus bucles de llenado por ctx -> buffer_size, por lo que solo la captura se ve afectada.\n\nfmt_type proviene de los descriptores de transmisión de audio del dispositivo, por lo que cualquier dispositivo que anuncie un formato de captura de Tipo II encuentra esto una vez que el espacio de usuario establece hw_params en el flujo.\n\nKASAN en 7.2.0-rc5 (arm64) con un dispositivo dummy_hcd/raw-gadget, un informe por transferencia entrante:\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\nCalcule buffer_size después de que se haya contabilizado el paquete delimitador, y limite el bucle de llenado por buffer_size, como ya hace prepare_silent_urb() en el lado de salida. Esto aumenta cada asignación de URB de Tipo II en un paquete de tamaño máximo.\n\nDescubierto por XBOW, clasificado por Baul Lee <[email protected]>"
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"sound/usb/endpoint.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "8fdff6a319e7dac757c558bd283dc4577e68cde7",
"lessThan": "6af5f29af7711233ae68d3b25c15d67478468900",
"versionType": "git",
"status": "affected"
},
{
"version": "8fdff6a319e7dac757c558bd283dc4577e68cde7",
"lessThan": "f1fbb50b99311b35c2e85cc70341d62082dca4b5",
"versionType": "git",
"status": "affected"
},
{
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"lessThan": "137bf034740e5a2734794908d0aff1e0bd7cee6e",
"versionType": "git",
"status": "affected"
},
{
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"lessThan": "6607f85242577f33d4540a0d1f4a6137f5367058",
"versionType": "git",
"status": "affected"
},
{
"version": "8fdff6a319e7dac757c558bd283dc4577e68cde7",
"lessThan": "ca22c94bdfc22c564ca2e11c87ba4d17ebeaaa9a",
"versionType": "git",
"status": "affected"
},
{
"version": "8fdff6a319e7dac757c558bd283dc4577e68cde7",
"lessThan": "0a235379825e1a6194e43861ee6658e5fc35686d",
"versionType": "git",
"status": "affected"
},
{
"version": "8fdff6a319e7dac757c558bd283dc4577e68cde7",
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"versionType": "git",
"status": "affected"
},
{
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"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"sound/usb/endpoint.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "3.5",
"status": "affected"
},
{
"version": "0",
"lessThan": "3.5",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.10.265",
"lessThanOrEqual": "5.10.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.216",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.183",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.152",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.104",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.45",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.1.9",
"lessThanOrEqual": "7.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-11-06T17:01:20.774649Z",
"id": "CVE-2026-74682",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
]
},
"references": [
{
"url": "https://git.kernel.org/stable/c/0a235379825e1a6194e43861ee6658e5fc35686d",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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{
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}