SEPTEMBER 8, 2026
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Case File

CVE-2026-63893

HIGH · CVSS 8.1 EPSS 0.39%

Source: NVD + CISA KEV + EPSS · Published 2026-07-19 · Last synced 2026-08-18

CyberRota Analysis

AI-Generated

The vulnerability in the Linux kernel affects the Thunderbolt subsystem, where a malicious XDomain peer can exploit a wraparound condition in the property entry validation, allowing them to read memory beyond allocated bounds. This can lead to unauthorized access to sensitive information, such as device and vendor names, through sysfs attributes. Organizations utilizing Linux systems with Thunderbolt support should prioritize patching this vulnerability to mitigate potential data leaks and maintain system integrity.

CVE
CVE-2026-63893
Severity
HIGH
CVSS
8.1
EPSS
0.39%
Linux

Original NVD 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.