CVE-2026-63893 (GCVE-0-2026-63893)
Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-08-05 12:36
VLAI
EPSS
VEX
Title
thunderbolt: property: Reject u32 wrap in tb_property_entry_valid()
Summary
In the Linux kernel, the following vulnerability has been resolved:
thunderbolt: property: Reject u32 wrap in tb_property_entry_valid()
entry->value is u32 and entry->length is u16; the sum is performed in
u32 and wraps. A malicious XDomain peer can pick
value = 0xffffff00, length = 0x100 so the sum 0x100000000 wraps to 0
and passes the > block_len check. tb_property_parse() then passes
entry->value to parse_dwdata() as a dword offset into the property
block, reading attacker-directed memory far past the allocation.
For TEXT-typed entries with the "deviceid" or "vendorid" keys this
lands in xd->device_name / xd->vendor_name and is readable back via
the per-XDomain device_name / vendor_name sysfs attributes; the leak
is NUL-bounded (kstrdup() stops at the first zero byte) and
untargeted (the attacker picks a delta, not an absolute address).
DATA-typed entries are parsed into property->value.data but not
generically surfaced to userspace.
Use check_add_overflow() so a wrapped sum is rejected.
Severity
8.1 (High)
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 6a63623621639acbb39bc2d9fb09559681716695
(git)
Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36 (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 9fee50c4e1e42f6d3cbe30df584f9f648f626071 (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 8d4a758b407ab3de3be86d1ceadfa35d717d30c7 (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 5c06a3043ad944f087bb2ae0aae28d820bb9f460 (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 31b98e503ecca8077e5247253dd5425ab84bc96d (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < a47784aee77f33f786dc5d7375db821bdae68792 (git) Affected: cdae7c07e3e3509eaabc18c1640a55dc5b99c179 , < 01deda0152066c6c955f0619114ea6afa070aaec (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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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: property: Reject u32 wrap in tb_property_entry_valid()\n\nentry-\u003evalue is u32 and entry-\u003elength is u16; the sum is performed in\nu32 and wraps. A malicious XDomain peer can pick\nvalue = 0xffffff00, length = 0x100 so the sum 0x100000000 wraps to 0\nand passes the \u003e block_len check. tb_property_parse() then passes\nentry-\u003evalue to parse_dwdata() as a dword offset into the property\nblock, reading attacker-directed memory far past the allocation.\n\nFor TEXT-typed entries with the \"deviceid\" or \"vendorid\" keys this\nlands in xd-\u003edevice_name / xd-\u003evendor_name and is readable back via\nthe per-XDomain device_name / vendor_name sysfs attributes; the leak\nis NUL-bounded (kstrdup() stops at the first zero byte) and\nuntargeted (the attacker picks a delta, not an absolute address).\nDATA-typed entries are parsed into property-\u003evalue.data but not\ngenerically surfaced to userspace.\n\nUse check_add_overflow() so a wrapped sum is rejected."
}
],
"metrics": [
{
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"baseScore": 8.1,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:A - A malicious Thunderbolt XDomain peer (adjacent host, dock, or in-line device on a direct Thunderbolt/USB4 link) delivers crafted PROPERTIES_RESPONSE data that the victim kernel parses during automatic XDomain discovery.\nAC:L - The peer fully controls property entry value/length fields and can reliably craft the u32 wrap (e.g. value=0xffffff00, length=0x100) without races or special memory layout.\nPR:N - Exploitation requires no privileges on the victim system; the attacker only needs to be the connected XDomain peer responding to the kernel-initiated property exchange, with no authentication on that control-plane path.\nUI:N - Once a Thunderbolt XDomain link exists, property fetching and parsing run automatically in the kernel handshake state machine without any additional victim user action at exploitation time.\nS:U - Impact is confined to the victim kernel/userspace boundary (kernel heap disclosure to local sysfs and possible kernel crash); it does not cross VM, IOMMU, or sandbox security boundaries.\nC:H - Integer-wrap bypass enables an out-of-bounds kernel memory read of up to entry-\u003elength dwords, which for deviceid/vendorid TEXT properties is copied into world-readable sysfs attributes, disclosing kernel heap contents.\nI:N - The bug is an out-of-bounds read via parse_dwdata(); destination buffers are properly sized kcalloc allocations, so there is no out-of-bounds write or integrity modification of victim kernel structures.\nA:H - Reading from block+0xffffff00 dwords (~4 GB past the allocation) will access unmapped kernel addresses, causing a kernel fault/oops/panic in addition to any information disclosure."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T12:36:59.715Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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{
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"title": "thunderbolt: property: Reject u32 wrap in tb_property_entry_valid()",
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"datePublished": "2026-07-19T14:55:04.288Z",
"dateReserved": "2026-07-19T07:54:57.019Z",
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"date": "2026-10-05",
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"lessThanOrEqual": "6.1.*",
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{
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{
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: property: Reject u32 wrap in tb_property_entry_valid()\n\nentry-\u003evalue is u32 and entry-\u003elength is u16; the sum is performed in\nu32 and wraps. A malicious XDomain peer can pick\nvalue = 0xffffff00, length = 0x100 so the sum 0x100000000 wraps to 0\nand passes the \u003e block_len check. tb_property_parse() then passes\nentry-\u003evalue to parse_dwdata() as a dword offset into the property\nblock, reading attacker-directed memory far past the allocation.\n\nFor TEXT-typed entries with the \"deviceid\" or \"vendorid\" keys this\nlands in xd-\u003edevice_name / xd-\u003evendor_name and is readable back via\nthe per-XDomain device_name / vendor_name sysfs attributes; the leak\nis NUL-bounded (kstrdup() stops at the first zero byte) and\nuntargeted (the attacker picks a delta, not an absolute address).\nDATA-typed entries are parsed into property-\u003evalue.data but not\ngenerically surfaced to userspace.\n\nUse check_add_overflow() so a wrapped sum is rejected."
}
],
"id": "CVE-2026-63893",
"lastModified": "2026-07-27T17:44:23.777",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "ADJACENT_NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.1,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
"version": "3.1"
},
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"impactScore": 5.2,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
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"published": "2026-07-19T16:17:06.710",
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{
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"url": "https://git.kernel.org/stable/c/a47784aee77f33f786dc5d7375db821bdae68792"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-07-21T20:54:29+00:00",
"cve": "CVE-2026-63893",
"id": "CVE-2026-63893",
"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 u32 wrap in tb_property_entry_valid()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63893.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-10-01T00:49:16Z",
"cve": "CVE-2026-63893",
"id": "CVE-2026-63893",
"initial_release_date": "2026-07-21T13:04:06Z",
"product_status:known_affected": "491",
"product_status:known_not_affected": "76",
"product_status:recommended": "465",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-63893",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-63893.json",
"version": "20"
}
}
}
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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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