CVE-2026-63896 (GCVE-0-2026-63896)
Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-07-19 14:55
VLAI
EPSS
VEX
Title
usb: gadget: composite: fix integer underflow in WebUSB GET_URL handling
Summary
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: composite: fix integer underflow in WebUSB GET_URL handling
The WebUSB GET_URL handler in composite_setup() narrows
landing_page_length to fit the host-supplied wLength using
landing_page_length = w_length
- WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH + landing_page_offset;
If wLength is smaller than WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH the
unsigned subtraction wraps, and the subsequent
memcpy(url_descriptor->URL,
cdev->landing_page + landing_page_offset,
landing_page_length - landing_page_offset);
ends up copying close to UINT_MAX bytes from cdev->landing_page into
cdev->req->buf. KASAN reports a slab-out-of-bounds in composite_setup
on the kmalloc-2k gadget_info allocation, and FORTIFY_SOURCE traps the
memcpy as a 4294967293-byte field-spanning write into
url_descriptor->URL (size 252).
A USB host can reach this from a single SETUP packet against any
gadget that has webusb/use=1 and a landingPage configured.
Handle the small-wLength case before the math: when the host requested
fewer bytes than the URL descriptor header, only the header is
meaningful and no URL bytes need to be copied. Setting
landing_page_length to landing_page_offset makes the existing memcpy a
no-op and leaves the descriptor returned to the host unchanged for all
larger wLength values.
Severity
No CVSS data available.
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
93c473948c588978cd55d9a3adad8b3e8057aa21 , < 046870ff6b6f7b743c953c061043a9b30700d491
(git)
Affected: 93c473948c588978cd55d9a3adad8b3e8057aa21 , < f5869dfaa89854dcf34121036294d42d6c7acb8f (git) Affected: 93c473948c588978cd55d9a3adad8b3e8057aa21 , < f8f5a8f48c7cae3fac85e04b593bd47939f9725f (git) Affected: 93c473948c588978cd55d9a3adad8b3e8057aa21 , < a20f0ccf45708af6e063c7234c215d364b00de25 (git) Affected: 93c473948c588978cd55d9a3adad8b3e8057aa21 , < 6c5dbc104dadd79fc2923497c20bae759a18758c (git) |
guessed | |
| Linux | Linux |
Affected:
6.3
Unaffected: 0 , < 6.3 (semver) Unaffected: 6.6.143 , ≤ 6.6.* (semver) Unaffected: 6.12.93 , ≤ 6.12.* (semver) Unaffected: 6.18.35 , ≤ 6.18.* (semver) Unaffected: 7.0.12 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/usb/gadget/composite.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "046870ff6b6f7b743c953c061043a9b30700d491",
"status": "affected",
"version": "93c473948c588978cd55d9a3adad8b3e8057aa21",
"versionType": "git"
},
{
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"status": "affected",
"version": "93c473948c588978cd55d9a3adad8b3e8057aa21",
"versionType": "git"
},
{
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"versionType": "git"
},
{
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"status": "affected",
"version": "93c473948c588978cd55d9a3adad8b3e8057aa21",
"versionType": "git"
},
{
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"status": "affected",
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"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/usb/gadget/composite.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.3"
},
{
"lessThan": "6.3",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.143",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.35",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.0.*",
"status": "unaffected",
"version": "7.0.12",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.143",
"versionStartIncluding": "6.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.93",
"versionStartIncluding": "6.3",
"vulnerable": true
},
{
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1",
"versionStartIncluding": "6.3",
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: composite: fix integer underflow in WebUSB GET_URL handling\n\nThe WebUSB GET_URL handler in composite_setup() narrows\nlanding_page_length to fit the host-supplied wLength using\n\n\tlanding_page_length = w_length\n\t\t- WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH + landing_page_offset;\n\nIf wLength is smaller than WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH the\nunsigned subtraction wraps, and the subsequent\n\n\tmemcpy(url_descriptor-\u003eURL,\n\t cdev-\u003elanding_page + landing_page_offset,\n\t landing_page_length - landing_page_offset);\n\nends up copying close to UINT_MAX bytes from cdev-\u003elanding_page into\ncdev-\u003ereq-\u003ebuf. KASAN reports a slab-out-of-bounds in composite_setup\non the kmalloc-2k gadget_info allocation, and FORTIFY_SOURCE traps the\nmemcpy as a 4294967293-byte field-spanning write into\nurl_descriptor-\u003eURL (size 252).\n\nA USB host can reach this from a single SETUP packet against any\ngadget that has webusb/use=1 and a landingPage configured.\n\nHandle the small-wLength case before the math: when the host requested\nfewer bytes than the URL descriptor header, only the header is\nmeaningful and no URL bytes need to be copied. Setting\nlanding_page_length to landing_page_offset makes the existing memcpy a\nno-op and leaves the descriptor returned to the host unchanged for all\nlarger wLength values."
}
],
"providerMetadata": {
"dateUpdated": "2026-07-19T14:55:06.152Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/046870ff6b6f7b743c953c061043a9b30700d491"
},
{
"url": "https://git.kernel.org/stable/c/f5869dfaa89854dcf34121036294d42d6c7acb8f"
},
{
"url": "https://git.kernel.org/stable/c/f8f5a8f48c7cae3fac85e04b593bd47939f9725f"
},
{
"url": "https://git.kernel.org/stable/c/a20f0ccf45708af6e063c7234c215d364b00de25"
},
{
"url": "https://git.kernel.org/stable/c/6c5dbc104dadd79fc2923497c20bae759a18758c"
}
],
"title": "usb: gadget: composite: fix integer underflow in WebUSB GET_URL handling",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-63896",
"datePublished": "2026-07-19T14:55:06.152Z",
"dateReserved": "2026-07-19T07:54:57.019Z",
"dateUpdated": "2026-07-19T14:55:06.152Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
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"cve": "CVE-2026-63896",
"date": "2026-09-21",
"epss": "0.00214",
"percentile": "0.12083"
},
"nvd": {
"cve": {
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{
"affectedData": [
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"product": "Linux",
"programFiles": [
"drivers/usb/gadget/composite.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"vendor": "Linux",
"versions": [
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"version": "0",
"versionType": "semver"
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"status": "unaffected",
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"versionType": "semver"
},
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"versionType": "semver"
},
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"versionType": "semver"
},
{
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"version": "7.0.12",
"versionType": "semver"
},
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"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix"
}
]
}
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}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: composite: fix integer underflow in WebUSB GET_URL handling\n\nThe WebUSB GET_URL handler in composite_setup() narrows\nlanding_page_length to fit the host-supplied wLength using\n\n\tlanding_page_length = w_length\n\t\t- WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH + landing_page_offset;\n\nIf wLength is smaller than WEBUSB_URL_DESCRIPTOR_HEADER_LENGTH the\nunsigned subtraction wraps, and the subsequent\n\n\tmemcpy(url_descriptor-\u003eURL,\n\t cdev-\u003elanding_page + landing_page_offset,\n\t landing_page_length - landing_page_offset);\n\nends up copying close to UINT_MAX bytes from cdev-\u003elanding_page into\ncdev-\u003ereq-\u003ebuf. KASAN reports a slab-out-of-bounds in composite_setup\non the kmalloc-2k gadget_info allocation, and FORTIFY_SOURCE traps the\nmemcpy as a 4294967293-byte field-spanning write into\nurl_descriptor-\u003eURL (size 252).\n\nA USB host can reach this from a single SETUP packet against any\ngadget that has webusb/use=1 and a landingPage configured.\n\nHandle the small-wLength case before the math: when the host requested\nfewer bytes than the URL descriptor header, only the header is\nmeaningful and no URL bytes need to be copied. Setting\nlanding_page_length to landing_page_offset makes the existing memcpy a\nno-op and leaves the descriptor returned to the host unchanged for all\nlarger wLength values."
}
],
"id": "CVE-2026-63896",
"lastModified": "2026-07-27T17:44:23.777",
"metrics": {},
"published": "2026-07-19T16:17:07.130",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/046870ff6b6f7b743c953c061043a9b30700d491"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/6c5dbc104dadd79fc2923497c20bae759a18758c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/a20f0ccf45708af6e063c7234c215d364b00de25"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f5869dfaa89854dcf34121036294d42d6c7acb8f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f8f5a8f48c7cae3fac85e04b593bd47939f9725f"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-08-07T12:45:08+00:00",
"cve": "CVE-2026-63896",
"id": "CVE-2026-63896",
"initial_release_date": "2026-07-19T00:00:00+00:00",
"product_status:known_affected": "76",
"product_status:known_not_affected": "198",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: usb: gadget: composite: fix integer underflow in WebUSB GET_URL handling",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63896.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-09-18T00:46:46Z",
"cve": "CVE-2026-63896",
"id": "CVE-2026-63896",
"initial_release_date": "2026-07-21T13:04:03Z",
"product_status:first_fixed": "2",
"product_status:known_affected": "424",
"product_status:known_not_affected": "326",
"product_status:recommended": "250",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-63896",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-63896.json",
"version": "9"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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