CVE-2026-80970
In the Linux kernel, the following vulnerability has been resolved:
ALSA: FCP: do not copy out an uninitialised init response
fcp_ioctl_init() allocates its response buffer with kmalloc() and copies the whole buffer back to userspace:
Nothing clears the buffer, and the only writer of its leading step0_resp_size bytes is the step-0 control transfer:
usb_fill_control_urb() does not set URB_SHORT_NOT_OK, so a short or zero-length data stage completes with status 0 and snd_usb_ctl_msg() returns a small actual_length. The only check is err < 0, so a short transfer is accepted as success.
snd_usb_ctl_msg() copies the full size back unconditionally:
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Bytes the device never wrote are therefore restored into resp unchanged and copied to userspace. step0_resp_size and step2_resp_size are each validated only to 1..255, so the caller also picks the slab cache, from kmalloc-8 up to kmalloc-512.
On 7.2.0-rc5 (arm64), device answering step 0 with a zero-length data stage, s0 = s2 = 255:
a8 c4 5f 80 00 80 ff ff is the little-endian kernel text address ffff8000805fc4a8. The step-2 window is unaffected, so the disclosure is exactly the step-0 region.
Zero the buffer, and require the step-0 transfer to deliver the full step0_resp_size bytes so a short data stage is reported as an error.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Detalles técnicos trazas, registros y código del informe original
buf_size = init.step0_resp_size + init.step2_resp_size; void *resp __free(kfree) = kmalloc(buf_size, GFP_KERNEL); ... if (copy_to_user(arg->resp, resp, buf_size)) return -EFAULT; err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), FCP_USB_REQ_STEP0, USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN, 0, private->bInterfaceNumber, step0_resp, private->step0_resp_size); if (err < 0) return err; buf = kmemdup(data, size, GFP_KERNEL); ... memcpy(data, buf, size); # init_on_alloc off, no spray step0 window [0,255): nonzero=94/255 000: 00 80 60 06 00 00 ff ff 18 00 00 00 57 01 ea 01 010: 08 78 22 13 00 00 ff ff a8 c4 5f 80 00 80 ff ff # same kernel, kmalloc-512 pre-seeded with an 8-byte tag step0 window [0,255): nonzero=219/255 tagbytes=232 # identical run, init_on_alloc=1 step0 window [0,255): nonzero=0/255 tagbytes=0 # all three runs step2 window [255,510): device words matched=62/62
CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-80970",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "46757a3e7d50dac923888e7fbe68377736f13c70",
"lessThan": "e9e52437120fb5f802152877ba20c4b406c9fa9e",
"versionType": "git"
},
{
"status": "affected",
"version": "46757a3e7d50dac923888e7fbe68377736f13c70",
"lessThan": "29ab2df278ab4f1d238cd9c1c393ee00db175cba",
"versionType": "git"
},
{
"status": "affected",
"version": "46757a3e7d50dac923888e7fbe68377736f13c70",
"lessThan": "4335e387786479889e6db691fe06d345e52ea536",
"versionType": "git"
}
],
"programFiles": [
"sound/usb/fcp.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.14"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.14",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.18.52",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.4",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"sound/usb/fcp.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-11T20:19:03.090",
"references": [
{
"url": "https://git.kernel.org/stable/c/29ab2df278ab4f1d238cd9c1c393ee00db175cba",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/4335e387786479889e6db691fe06d345e52ea536",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e9e52437120fb5f802152877ba20c4b406c9fa9e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: FCP: do not copy out an uninitialised init response\n\nfcp_ioctl_init() allocates its response buffer with kmalloc() and copies\nthe whole buffer back to userspace:\n\n\tbuf_size = init.step0_resp_size + init.step2_resp_size;\n\n\tvoid *resp __free(kfree) =\n\t\tkmalloc(buf_size, GFP_KERNEL);\n\t...\n\tif (copy_to_user(arg->resp, resp, buf_size))\n\t\treturn -EFAULT;\n\nNothing clears the buffer, and the only writer of its leading\nstep0_resp_size bytes is the step-0 control transfer:\n\n\terr = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0),\n\t\tFCP_USB_REQ_STEP0,\n\t\tUSB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,\n\t\t0, private->bInterfaceNumber,\n\t\tstep0_resp, private->step0_resp_size);\n\tif (err < 0)\n\t\treturn err;\n\nusb_fill_control_urb() does not set URB_SHORT_NOT_OK, so a short or\nzero-length data stage completes with status 0 and snd_usb_ctl_msg()\nreturns a small actual_length. The only check is err < 0, so a short\ntransfer is accepted as success.\n\nsnd_usb_ctl_msg() copies the full size back unconditionally:\n\n\tbuf = kmemdup(data, size, GFP_KERNEL);\n\t...\n\tmemcpy(data, buf, size);\n\nBytes the device never wrote are therefore restored into resp unchanged\nand copied to userspace. step0_resp_size and step2_resp_size are each\nvalidated only to 1..255, so the caller also picks the slab cache, from\nkmalloc-8 up to kmalloc-512.\n\nOn 7.2.0-rc5 (arm64), device answering step 0 with a zero-length data\nstage, s0 = s2 = 255:\n\n # init_on_alloc off, no spray\n step0 window [0,255): nonzero=94/255\n 000: 00 80 60 06 00 00 ff ff 18 00 00 00 57 01 ea 01\n 010: 08 78 22 13 00 00 ff ff a8 c4 5f 80 00 80 ff ff\n\n # same kernel, kmalloc-512 pre-seeded with an 8-byte tag\n step0 window [0,255): nonzero=219/255 tagbytes=232\n\n # identical run, init_on_alloc=1\n step0 window [0,255): nonzero=0/255 tagbytes=0\n\n # all three runs\n step2 window [255,510): device words matched=62/62\n\na8 c4 5f 80 00 80 ff ff is the little-endian kernel text address\nffff8000805fc4a8. The step-2 window is unaffected, so the disclosure is\nexactly the step-0 region.\n\nZero the buffer, and require the step-0 transfer to deliver the full\nstep0_resp_size bytes so a short data stage is reported as an error.\n\nDiscovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>"
}
],
"lastModified": "2026-09-14T13:18:51.770",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}