CVE-2026-63891
thunderbolt: property: Cap recursion depth in __tb_property_parse_dir()
Description
In the Linux kernel, the following vulnerability has been resolved: thunderbolt: property: Cap recursion depth in __tb_property_parse_dir() A DIRECTORY entry's value field is used as the dir_offset for a recursive call into __tb_property_parse_dir() with no depth counter. A crafted peer that chains DIRECTORY entries into a back-reference loop drives the parser until the kernel stack is exhausted and the guard page fires. Any untrusted XDomain peer (cable, dock, in-line inspector, adjacent host) that reaches the PROPERTIES_REQUEST control-plane exchange can trigger this without authentication. Thread a depth counter through tb_property_parse() and __tb_property_parse_dir(), and reject blocks that exceed TB_PROPERTY_MAX_DEPTH = 8. That is comfortably larger than any observed legitimate XDomain layout. Operators who do not need XDomain host-to-host discovery can disable the path entirely with thunderbolt.xdomain=0 on the kernel command line.
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
Solution
- Apply kernel patch to add recursion depth counter.
- Set thunderbolt.xdomain=0 on kernel command line.
- Reject blocks exceeding recursion depth limit.
- Ensure legitimate XDomain layouts are within limits.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-63891.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-63891 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-2026-63891
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-2026-63891 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-63891 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.
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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': '2b5f47a710172c962ef42d1b732b04d2ad0dce21', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': '95839a67ea56ca35732aad7f711404a3127cfe2d', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': '0a84ab9271936c11e84e511bb52fc5682f8b6726', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': 'b4621e5ef63405c317a84b711faf3bd75b3c6a94', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': 'f31c6d220f455b5af63590302b30e1b932d14599', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': '830c8a9b467e7d3a158483d37fa7dc13892b293a', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': 'ed9455ef4bd9babc90f92e526abe3fb68c1a8709', 'versionType': 'git'}, {'status': 'affected', 'version': 'cdae7c07e3e3509eaabc18c1640a55dc5b99c179', 'lessThan': '928abe19fbf0127003abcb1ea69cabc1c897d0ab', '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: Cap recursion depth in __tb_property_parse_dir() A DIRECTORY entry's value field is used as the dir_offset for a recursive call into __tb_property_parse_dir() with no depth counter. A crafted peer that chains DIRECTORY entries into a back-reference loop drives the parser until the kernel stack is exhausted and the guard page fires. Any untrusted XDomain peer (cable, dock, in-line inspector, adjacent host) that reaches the PROPERTIES_REQUEST control-plane exchange can trigger this without authentication. Thread a depth counter through tb_property_parse() and __tb_property_parse_dir(), and reject blocks that exceed TB_PROPERTY_MAX_DEPTH = 8. That is comfortably larger than any observed legitimate XDomain layout. Operators who do not need XDomain host-to-host discovery can disable the path entirely with thunderbolt.xdomain=0 on the kernel command line. Added Reference https://git.kernel.org/stable/c/0a84ab9271936c11e84e511bb52fc5682f8b6726 Added Reference https://git.kernel.org/stable/c/2b5f47a710172c962ef42d1b732b04d2ad0dce21 Added Reference https://git.kernel.org/stable/c/830c8a9b467e7d3a158483d37fa7dc13892b293a Added Reference https://git.kernel.org/stable/c/928abe19fbf0127003abcb1ea69cabc1c897d0ab Added Reference https://git.kernel.org/stable/c/95839a67ea56ca35732aad7f711404a3127cfe2d Added Reference https://git.kernel.org/stable/c/b4621e5ef63405c317a84b711faf3bd75b3c6a94 Added Reference https://git.kernel.org/stable/c/ed9455ef4bd9babc90f92e526abe3fb68c1a8709 Added Reference https://git.kernel.org/stable/c/f31c6d220f455b5af63590302b30e1b932d14599