CVE-2026-63893: In the Linux kernel, the following vulnerability has been resolved: thunderbolt: property: Reject u32 wrap in tb_property_entry_valid() entry->value...

Description

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.

Metrics

CVSS 3.1

8.1/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

EPSS Probability

0.36%

28.6th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

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

Vendor	Product	Versions
Linux	Linux	>= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 6a63623621639acbb39bc2d9fb09559681716695; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 9fee50c4e1e42f6d3cbe30df584f9f648f626071; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 8d4a758b407ab3de3be86d1ceadfa35d717d30c7; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 5c06a3043ad944f087bb2ae0aae28d820bb9f460; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 31b98e503ecca8077e5247253dd5425ab84bc96d; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < a47784aee77f33f786dc5d7375db821bdae68792; >= cdae7c07e3e3509eaabc18c1640a55dc5b99c179, < 01deda0152066c6c955f0619114ea6afa070aaec
Linux	Linux	4.15

References

Timeline

Published: Jul 19, 2026
Last Modified: Jul 27, 2026
Status: Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-63893?

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.

How severe is CVE-2026-63893?

CVE-2026-63893 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.36% probability of exploitation in the next 30 days.

How do I fix CVE-2026-63893?

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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