CVE-2026-63891
Vulnerability Scoring
Analysis In Progress
CVE-2026-63891 Vulnerability Analysis & Exploit Details
CVE-2026-63891
Attack Complexity Details
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Attack Complexity:
Attack Complexity Analysis In Progress
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Attack Vector:
Attack Vector Under Analysis
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Privileges Required:
None
No authentication is required for exploitation.
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Scope:
Impact is confined to the initially vulnerable component.
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User Interaction:
None
No user interaction is necessary for exploitation.
CVE-2026-63891 Details
Status: Received on 19 Jul 2026, 16:17 UTC
Published on: 19 Jul 2026, 16:17 UTC
CVSS Release:
CVE-2026-63891 Vulnerability Summary
CVE-2026-63891: 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.
Assessing the Risk of CVE-2026-63891
Access Complexity Graph
The exploitability of CVE-2026-63891 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
Exploitability Analysis for CVE-2026-63891
No exploitability data is available for CVE-2026-63891.
Understanding AC and PR
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
CVSS Score Breakdown Chart
Above is the CVSS Sub-score Breakdown for CVE-2026-63891, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
CIA Impact Analysis
Below is the Impact Analysis for CVE-2026-63891, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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Confidentiality:
None
CVE-2026-63891 does not compromise confidentiality.
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Integrity:
None
CVE-2026-63891 does not impact data integrity.
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Availability:
None
CVE-2026-63891 does not affect system availability.
CVE-2026-63891 References
External References
- https://git.kernel.org/stable/c/0a84ab9271936c11e84e511bb52fc5682f8b6726
- https://git.kernel.org/stable/c/2b5f47a710172c962ef42d1b732b04d2ad0dce21
- https://git.kernel.org/stable/c/830c8a9b467e7d3a158483d37fa7dc13892b293a
- https://git.kernel.org/stable/c/928abe19fbf0127003abcb1ea69cabc1c897d0ab
- https://git.kernel.org/stable/c/95839a67ea56ca35732aad7f711404a3127cfe2d
- https://git.kernel.org/stable/c/b4621e5ef63405c317a84b711faf3bd75b3c6a94
- https://git.kernel.org/stable/c/ed9455ef4bd9babc90f92e526abe3fb68c1a8709
- https://git.kernel.org/stable/c/f31c6d220f455b5af63590302b30e1b932d14599
CWE Common Weakness Enumeration
Unknown
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