0.0
NA
CVE-2026-63892
thunderbolt: property: Reject dir_len < 4 to prevent size_t underflow
Description

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.

INFO

Published Date :

July 19, 2026, 4:17 p.m.

Last Modified :

July 27, 2026, 5:44 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2026-63892 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
Solution
Address size_t underflow by rejecting small dir_len values and correctly initializing lists.
  • Reject dir_len values less than 4.
  • Initialize lists before allocation.
  • Apply provided kernel patch.
  • Update Linux kernel.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-63892 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-63892 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-63892 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2026-63892 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jul. 19, 2026

    Action Type Old Value New Value
    Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': '37abc4504fa19d8f9f1e87792e8a2b8fdb308e40', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': 'e2d4d51cf5785815fa4e91e0c019e3eb2506a84c', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': 'de618299190b418291609e6921557253bd417e25', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': '5506c825f14d810f0690b1f4367cb7249ebb387a', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': '542a13890b742099c461d70920e97b14e568f6ec', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': 'd548179adcc87e1bc66b17e00352a1f536e76065', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': '3bec49ca55e08fb085cc4318f24b1b37eaab28cb', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': 'de21b59c29e31c5108ddc04210631bbfab81b997', 'versionType': 'git'}], 'programFiles': ['drivers/thunderbolt/property.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '4.15'}, {'status': 'unaffected', 'version': '0', 'lessThan': '4.15', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.259', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.210', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.176', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.143', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.93', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.35', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.0.12', 'versionType': 'semver', 'lessThanOrEqual': '7.0.*'}, {'status': 'unaffected', 'version': '7.1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['drivers/thunderbolt/property.c'], 'defaultStatus': 'affected'}]
    Added Description 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.
    Added Reference https://git.kernel.org/stable/c/37abc4504fa19d8f9f1e87792e8a2b8fdb308e40
    Added Reference https://git.kernel.org/stable/c/3bec49ca55e08fb085cc4318f24b1b37eaab28cb
    Added Reference https://git.kernel.org/stable/c/542a13890b742099c461d70920e97b14e568f6ec
    Added Reference https://git.kernel.org/stable/c/5506c825f14d810f0690b1f4367cb7249ebb387a
    Added Reference https://git.kernel.org/stable/c/d548179adcc87e1bc66b17e00352a1f536e76065
    Added Reference https://git.kernel.org/stable/c/de21b59c29e31c5108ddc04210631bbfab81b997
    Added Reference https://git.kernel.org/stable/c/de618299190b418291609e6921557253bd417e25
    Added Reference https://git.kernel.org/stable/c/e2d4d51cf5785815fa4e91e0c019e3eb2506a84c
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.