CVE-2025-40004 (GCVE-0-2025-40004)
Vulnerability from cvelistv5 – Published: 2025-10-20 05:26 – Updated: 2026-05-11 21:40
VLAI
EPSS
VEX
Title
net/9p: Fix buffer overflow in USB transport layer
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/9p: Fix buffer overflow in USB transport layer
A buffer overflow vulnerability exists in the USB 9pfs transport layer
where inconsistent size validation between packet header parsing and
actual data copying allows a malicious USB host to overflow heap buffers.
The issue occurs because:
- usb9pfs_rx_header() validates only the declared size in packet header
- usb9pfs_rx_complete() uses req->actual (actual received bytes) for
memcpy
This allows an attacker to craft packets with small declared size
(bypassing validation) but large actual payload (triggering overflow
in memcpy).
Add validation in usb9pfs_rx_complete() to ensure req->actual does not
exceed the buffer capacity before copying data.
Severity
No CVSS data available.
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
a3be076dc174d9022a71a12554feb4c97b5c4d5c , < 0da18d49f874d444ad83c8a546fa33bfcf2f582c
(git)
Affected: a3be076dc174d9022a71a12554feb4c97b5c4d5c , < df8462f0fc045b4475dc494a5787a03c972ba2a2 (git) Affected: a3be076dc174d9022a71a12554feb4c97b5c4d5c , < c04db81cd0288dfc68b7a0f7d09bd49b40bba451 (git) |
guessed | |
| Linux | Linux |
Affected:
6.12
Unaffected: 0 , < 6.12 (semver) Unaffected: 6.12.53 , ≤ 6.12.* (semver) Unaffected: 6.17.3 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/9p/trans_usbg.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "0da18d49f874d444ad83c8a546fa33bfcf2f582c",
"status": "affected",
"version": "a3be076dc174d9022a71a12554feb4c97b5c4d5c",
"versionType": "git"
},
{
"lessThan": "df8462f0fc045b4475dc494a5787a03c972ba2a2",
"status": "affected",
"version": "a3be076dc174d9022a71a12554feb4c97b5c4d5c",
"versionType": "git"
},
{
"lessThan": "c04db81cd0288dfc68b7a0f7d09bd49b40bba451",
"status": "affected",
"version": "a3be076dc174d9022a71a12554feb4c97b5c4d5c",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/9p/trans_usbg.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.12"
},
{
"lessThan": "6.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.53",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.17.*",
"status": "unaffected",
"version": "6.17.3",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.53",
"versionStartIncluding": "6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.17.3",
"versionStartIncluding": "6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18",
"versionStartIncluding": "6.12",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/9p: Fix buffer overflow in USB transport layer\n\nA buffer overflow vulnerability exists in the USB 9pfs transport layer\nwhere inconsistent size validation between packet header parsing and\nactual data copying allows a malicious USB host to overflow heap buffers.\n\nThe issue occurs because:\n- usb9pfs_rx_header() validates only the declared size in packet header\n- usb9pfs_rx_complete() uses req-\u003eactual (actual received bytes) for\nmemcpy\n\nThis allows an attacker to craft packets with small declared size\n(bypassing validation) but large actual payload (triggering overflow\nin memcpy).\n\nAdd validation in usb9pfs_rx_complete() to ensure req-\u003eactual does not\nexceed the buffer capacity before copying data."
}
],
"providerMetadata": {
"dateUpdated": "2026-05-11T21:40:36.949Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/0da18d49f874d444ad83c8a546fa33bfcf2f582c"
},
{
"url": "https://git.kernel.org/stable/c/df8462f0fc045b4475dc494a5787a03c972ba2a2"
},
{
"url": "https://git.kernel.org/stable/c/c04db81cd0288dfc68b7a0f7d09bd49b40bba451"
}
],
"title": "net/9p: Fix buffer overflow in USB transport layer",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-40004",
"datePublished": "2025-10-20T05:26:08.787Z",
"dateReserved": "2025-04-16T07:20:57.151Z",
"dateUpdated": "2026-05-11T21:40:36.949Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2025-40004",
"date": "2026-10-22",
"epss": "0.00267",
"percentile": "0.17838"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/9p/trans_usbg.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "0da18d49f874d444ad83c8a546fa33bfcf2f582c",
"status": "affected",
"version": "a3be076dc174d9022a71a12554feb4c97b5c4d5c",
"versionType": "git"
},
{
"lessThan": "df8462f0fc045b4475dc494a5787a03c972ba2a2",
"status": "affected",
"version": "a3be076dc174d9022a71a12554feb4c97b5c4d5c",
"versionType": "git"
},
{
"lessThan": "c04db81cd0288dfc68b7a0f7d09bd49b40bba451",
"status": "affected",
"version": "a3be076dc174d9022a71a12554feb4c97b5c4d5c",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/9p/trans_usbg.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.12"
},
{
"lessThan": "6.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.53",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.17.*",
"status": "unaffected",
"version": "6.17.3",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/9p: Fix buffer overflow in USB transport layer\n\nA buffer overflow vulnerability exists in the USB 9pfs transport layer\nwhere inconsistent size validation between packet header parsing and\nactual data copying allows a malicious USB host to overflow heap buffers.\n\nThe issue occurs because:\n- usb9pfs_rx_header() validates only the declared size in packet header\n- usb9pfs_rx_complete() uses req-\u003eactual (actual received bytes) for\nmemcpy\n\nThis allows an attacker to craft packets with small declared size\n(bypassing validation) but large actual payload (triggering overflow\nin memcpy).\n\nAdd validation in usb9pfs_rx_complete() to ensure req-\u003eactual does not\nexceed the buffer capacity before copying data."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnet/9p: Solucionar desbordamiento de b\u00fafer en la capa de transporte USB\n\nExiste una vulnerabilidad de desbordamiento de b\u00fafer en la capa de transporte USB 9pfs donde una validaci\u00f3n de tama\u00f1o inconsistente entre el an\u00e1lisis de la cabecera del paquete y la copia real de datos permite a un host USB malicioso desbordar los b\u00faferes de la pila.\n\nEl problema ocurre porque:\n- usb9pfs_rx_header() valida solo el tama\u00f1o declarado en la cabecera del paquete\n- usb9pfs_rx_complete() usa req-\u003eactual (bytes reales recibidos) para memcpy\n\nEsto permite a un atacante crear paquetes con un tama\u00f1o declarado peque\u00f1o (eludiendo la validaci\u00f3n) pero con una carga \u00fatil real grande (desencadenando un desbordamiento en memcpy).\n\nA\u00f1adir validaci\u00f3n en usb9pfs_rx_complete() para asegurar que req-\u003eactual no exceda la capacidad del b\u00fafer antes de copiar los datos."
}
],
"id": "CVE-2025-40004",
"lastModified": "2026-10-19T21:10:00.160",
"metrics": {},
"published": "2025-10-20T06:15:36.280",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/0da18d49f874d444ad83c8a546fa33bfcf2f582c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/c04db81cd0288dfc68b7a0f7d09bd49b40bba451"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/df8462f0fc045b4475dc494a5787a03c972ba2a2"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Deferred"
}
},
"redhat_vex": {
"aggregate_severity": "None",
"current_release_date": "2026-06-30T10:24:30+00:00",
"cve": "CVE-2025-40004",
"id": "CVE-2025-40004",
"initial_release_date": "2025-10-20T00:00:00+00:00",
"product_status:known_not_affected": "274",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: net/9p: Fix buffer overflow in USB transport layer",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40004.json",
"version": "3"
}
}
}
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