CVE-2026-63892 (GCVE-0-2026-63892)
Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-07-19 14:55
VLAI
EPSS
VEX
Title
thunderbolt: property: Reject dir_len < 4 to prevent size_t underflow
Summary
In the Linux kernel, the following vulnerability has been resolved:
thunderbolt: property: Reject dir_len < 4 to prevent size_t underflow
On the non-root path, __tb_property_parse_dir() takes dir_len from
entry->length (u16 widened to size_t). Two distinct OOB conditions
follow when entry->length < 4:
1. The non-root path begins with kmemdup(&block[dir_offset],
sizeof(*dir->uuid), ...) which always reads 4 dwords from
dir_offset. tb_property_entry_valid() only enforces
dir_offset + entry->length <= block_len, so a crafted entry
with dir_offset close to the end of the property block and
entry->length in 0..3 passes that gate but lets the UUID copy
run off the block (e.g. dir_offset = 497, dir_len = 3 in a
500-dword block reads block[497..501]).
2. After the kmemdup, content_len = dir_len - 4 underflows size_t
to ~SIZE_MAX, nentries becomes SIZE_MAX / 4, and the entry
walk runs OOB on each iteration until an entry fails
validation or the kernel oopses on an unmapped page.
Reject dir_len < 4 on the non-root path *before* the UUID kmemdup,
which closes both holes.
Also move INIT_LIST_HEAD(&dir->properties) up to immediately after
the dir allocation so the new error-return path (and the existing
uuid-alloc failure path) calling tb_property_free_dir() sees a
walkable list rather than the zero-initialized NULL next/prev that
list_for_each_entry_safe() would oops on.
Severity
No CVSS data available.
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 37abc4504fa19d8f9f1e87792e8a2b8fdb308e40
(git)
Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < e2d4d51cf5785815fa4e91e0c019e3eb2506a84c (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < de618299190b418291609e6921557253bd417e25 (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 5506c825f14d810f0690b1f4367cb7249ebb387a (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 542a13890b742099c461d70920e97b14e568f6ec (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < d548179adcc87e1bc66b17e00352a1f536e76065 (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 3bec49ca55e08fb085cc4318f24b1b37eaab28cb (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < de21b59c29e31c5108ddc04210631bbfab81b997 (git) |
guessed | |
| Linux | Linux |
Affected:
4.15
Unaffected: 0 , < 4.15 (semver) Unaffected: 5.10.259 , ≤ 5.10.* (semver) Unaffected: 5.15.210 , ≤ 5.15.* (semver) Unaffected: 6.1.176 , ≤ 6.1.* (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 |
{
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},
{
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"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.210",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.176",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.143",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver"
},
{
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"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": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.259",
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},
{
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},
{
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{
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{
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{
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}
],
"negate": false,
"operator": "OR"
}
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}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: property: Reject dir_len \u003c 4 to prevent size_t underflow\n\nOn the non-root path, __tb_property_parse_dir() takes dir_len from\nentry-\u003elength (u16 widened to size_t). Two distinct OOB conditions\nfollow when entry-\u003elength \u003c 4:\n\n1. The non-root path begins with kmemdup(\u0026block[dir_offset],\n sizeof(*dir-\u003euuid), ...) which always reads 4 dwords from\n dir_offset. tb_property_entry_valid() only enforces\n dir_offset + entry-\u003elength \u003c= block_len, so a crafted entry\n with dir_offset close to the end of the property block and\n entry-\u003elength in 0..3 passes that gate but lets the UUID copy\n run off the block (e.g. dir_offset = 497, dir_len = 3 in a\n 500-dword block reads block[497..501]).\n\n2. After the kmemdup, content_len = dir_len - 4 underflows size_t\n to ~SIZE_MAX, nentries becomes SIZE_MAX / 4, and the entry\n walk runs OOB on each iteration until an entry fails\n validation or the kernel oopses on an unmapped page.\n\nReject dir_len \u003c 4 on the non-root path *before* the UUID kmemdup,\nwhich closes both holes.\n\nAlso move INIT_LIST_HEAD(\u0026dir-\u003eproperties) up to immediately after\nthe dir allocation so the new error-return path (and the existing\nuuid-alloc failure path) calling tb_property_free_dir() sees a\nwalkable list rather than the zero-initialized NULL next/prev that\nlist_for_each_entry_safe() would oops on."
}
],
"providerMetadata": {
"dateUpdated": "2026-07-19T14:55:03.568Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/37abc4504fa19d8f9f1e87792e8a2b8fdb308e40"
},
{
"url": "https://git.kernel.org/stable/c/e2d4d51cf5785815fa4e91e0c019e3eb2506a84c"
},
{
"url": "https://git.kernel.org/stable/c/de618299190b418291609e6921557253bd417e25"
},
{
"url": "https://git.kernel.org/stable/c/5506c825f14d810f0690b1f4367cb7249ebb387a"
},
{
"url": "https://git.kernel.org/stable/c/542a13890b742099c461d70920e97b14e568f6ec"
},
{
"url": "https://git.kernel.org/stable/c/d548179adcc87e1bc66b17e00352a1f536e76065"
},
{
"url": "https://git.kernel.org/stable/c/3bec49ca55e08fb085cc4318f24b1b37eaab28cb"
},
{
"url": "https://git.kernel.org/stable/c/de21b59c29e31c5108ddc04210631bbfab81b997"
}
],
"title": "thunderbolt: property: Reject dir_len \u003c 4 to prevent size_t underflow",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2026-63892",
"datePublished": "2026-07-19T14:55:03.568Z",
"dateReserved": "2026-07-19T07:54:57.019Z",
"dateUpdated": "2026-07-19T14:55:03.568Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-63892",
"date": "2026-09-21",
"epss": "0.00229",
"percentile": "0.13988"
},
"nvd": {
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"defaultStatus": "unaffected",
"product": "Linux",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"versionType": "git"
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"versionType": "git"
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"versionType": "git"
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"versionType": "git"
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{
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"versionType": "git"
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.15"
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{
"lessThan": "4.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.259",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.210",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.176",
"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"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: property: Reject dir_len \u003c 4 to prevent size_t underflow\n\nOn the non-root path, __tb_property_parse_dir() takes dir_len from\nentry-\u003elength (u16 widened to size_t). Two distinct OOB conditions\nfollow when entry-\u003elength \u003c 4:\n\n1. The non-root path begins with kmemdup(\u0026block[dir_offset],\n sizeof(*dir-\u003euuid), ...) which always reads 4 dwords from\n dir_offset. tb_property_entry_valid() only enforces\n dir_offset + entry-\u003elength \u003c= block_len, so a crafted entry\n with dir_offset close to the end of the property block and\n entry-\u003elength in 0..3 passes that gate but lets the UUID copy\n run off the block (e.g. dir_offset = 497, dir_len = 3 in a\n 500-dword block reads block[497..501]).\n\n2. After the kmemdup, content_len = dir_len - 4 underflows size_t\n to ~SIZE_MAX, nentries becomes SIZE_MAX / 4, and the entry\n walk runs OOB on each iteration until an entry fails\n validation or the kernel oopses on an unmapped page.\n\nReject dir_len \u003c 4 on the non-root path *before* the UUID kmemdup,\nwhich closes both holes.\n\nAlso move INIT_LIST_HEAD(\u0026dir-\u003eproperties) up to immediately after\nthe dir allocation so the new error-return path (and the existing\nuuid-alloc failure path) calling tb_property_free_dir() sees a\nwalkable list rather than the zero-initialized NULL next/prev that\nlist_for_each_entry_safe() would oops on."
}
],
"id": "CVE-2026-63892",
"lastModified": "2026-07-27T17:44:23.777",
"metrics": {},
"published": "2026-07-19T16:17:06.577",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/37abc4504fa19d8f9f1e87792e8a2b8fdb308e40"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3bec49ca55e08fb085cc4318f24b1b37eaab28cb"
},
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},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/5506c825f14d810f0690b1f4367cb7249ebb387a"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d548179adcc87e1bc66b17e00352a1f536e76065"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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},
{
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"url": "https://git.kernel.org/stable/c/de618299190b418291609e6921557253bd417e25"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/e2d4d51cf5785815fa4e91e0c019e3eb2506a84c"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-07-21T20:54:23+00:00",
"cve": "CVE-2026-63892",
"id": "CVE-2026-63892",
"initial_release_date": "2026-07-19T00:00:00+00:00",
"product_status:known_not_affected": "274",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: thunderbolt: property: Reject dir_len \u003c 4 to prevent size_t underflow",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63892.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-09-18T00:46:51Z",
"cve": "CVE-2026-63892",
"id": "CVE-2026-63892",
"initial_release_date": "2026-07-21T13:04:07Z",
"product_status:first_fixed": "25",
"product_status:known_affected": "611",
"product_status:known_not_affected": "139",
"product_status:recommended": "250",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-63892",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-63892.json",
"version": "10"
}
}
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- 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 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.
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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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