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CVE-2026-63891

UnknownEPSS 0.26%

Last modified

CVE-2026-63891 is a vulnerability of currently unknown severity. 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. EPSS estimates a 0.26% chance of exploitation in the next 30 days.

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.

Metrics

EPSS Probability
0.26%

18.0th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 2b5f47a710172c962ef42d1b732b04d2ad0dce21; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 95839a67ea56ca35732aad7f711404a3127cfe2d; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 0a84ab9271936c11e84e511bb52fc5682f8b6726; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < b4621e5ef63405c317a84b711faf3bd75b3c6a94; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < f31c6d220f455b5af63590302b30e1b932d14599; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 830c8a9b467e7d3a158483d37fa7dc13892b293a; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < ed9455ef4bd9babc90f92e526abe3fb68c1a8709; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 928abe19fbf0127003abcb1ea69cabc1c897d0ab
LinuxLinux4.15

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is 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.
How severe is CVE-2026-63891?
Severity scoring for CVE-2026-63891 is pending analysis. The EPSS model estimates a 0.26% probability of exploitation in the next 30 days.
How do I fix CVE-2026-63891?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST