---
id: CVE-2026-63893
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 X…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 <
    6a63623621639acbb39bc2d9fb09559681716695
  - >-
    Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 <
    e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36
  - >-
    Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 <
    9fee50c4e1e42f6d3cbe30df584f9f648f626071
  - >-
    Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 <
    8d4a758b407ab3de3be86d1ceadfa35d717d30c7
  - >-
    Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 <
    5c06a3043ad944f087bb2ae0aae28d820bb9f460
  - >-
    Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 <
    31b98e503ecca8077e5247253dd5425ab84bc96d
  - >-
    Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 <
    a47784aee77f33f786dc5d7375db821bdae68792
  - >-
    Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 <
    01deda0152066c6c955f0619114ea6afa070aaec
  - Linux 4.15
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-16T15:33:06.328646Z'
published: '2026-07-19'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:42:10.643Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-63893'
references:
  - url: 'https://git.kernel.org/stable/c/6a63623621639acbb39bc2d9fb09559681716695'
  - url: 'https://git.kernel.org/stable/c/e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36'
  - url: 'https://git.kernel.org/stable/c/9fee50c4e1e42f6d3cbe30df584f9f648f626071'
  - url: 'https://git.kernel.org/stable/c/8d4a758b407ab3de3be86d1ceadfa35d717d30c7'
  - url: 'https://git.kernel.org/stable/c/5c06a3043ad944f087bb2ae0aae28d820bb9f460'
  - url: 'https://git.kernel.org/stable/c/31b98e503ecca8077e5247253dd5425ab84bc96d'
  - url: 'https://git.kernel.org/stable/c/a47784aee77f33f786dc5d7375db821bdae68792'
  - url: 'https://git.kernel.org/stable/c/01deda0152066c6c955f0619114ea6afa070aaec'
tags:
  - cve.org
epss: 0.00386
epssPercentile: 0.31074
ingestedAt: '2026-10-16T17:24:46.773Z'
---

## Overview

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.

## Affected

- `Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 6a63623621639acbb39bc2d9fb09559681716695`
- `Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36`
- `Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 9fee50c4e1e42f6d3cbe30df584f9f648f626071`
- `Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 8d4a758b407ab3de3be86d1ceadfa35d717d30c7`
- `Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 5c06a3043ad944f087bb2ae0aae28d820bb9f460`
- `Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 31b98e503ecca8077e5247253dd5425ab84bc96d`
- `Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < a47784aee77f33f786dc5d7375db821bdae68792`
- `Linux >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179 < 01deda0152066c6c955f0619114ea6afa070aaec`
- `Linux 4.15`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.