CVE-2026-53147 in Linux
Summary
by MITRE • 06/25/2026
In the Linux kernel, the following vulnerability has been resolved:
thunderbolt: Validate XDomain request packet size before type cast
tb_xdp_handle_request() casts the received packet buffer to protocol-specific structs without verifying that the allocation is large enough for the target type. A peer can send a minimal XDomain packet that passes the generic header length check but is shorter than the struct accessed after the cast, causing out-of- bounds reads from the kmemdup allocation.
Plumb the packet length through xdomain_request_work and validate it against the expected struct size before each cast.
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Analysis
by VulDB Data Team • 06/26/2026
The vulnerability identified in the Linux kernel represents a critical buffer overflow condition within the thunderbolt subsystem that stems from inadequate input validation during XDomain request processing. This flaw exists in the tb_xdp_handle_request() function where packet buffers are typecast to protocol-specific structures without proper bounds checking against the actual packet size. The issue manifests when peer devices send malformed XDomain packets that pass initial header length validations but contain insufficient data to satisfy the memory layout requirements of the targeted protocol structures.
The technical implementation of this vulnerability exploits a classic out-of-bounds read scenario where the kernel performs kmemdup allocation based on an unvalidated packet length parameter. When the code subsequently casts this buffer to specific protocol structures without verifying that sufficient data exists within the allocated memory region, it creates a condition where reads occur beyond the bounds of the originally allocated buffer. This type of vulnerability falls under CWE-129 and CWE-787 categories, representing improper input validation and out-of-bounds read conditions respectively. The flaw demonstrates a fundamental weakness in defensive programming practices where assumptions about incoming data integrity are not properly validated before memory operations.
The operational impact of this vulnerability extends beyond simple data corruption, potentially enabling privilege escalation or information disclosure within the kernel space. Attackers can leverage this condition to read arbitrary kernel memory locations through carefully crafted XDomain packets, which could expose sensitive kernel data structures, credentials, or cryptographic keys. The vulnerability affects systems utilizing thunderbolt hardware that process XDomain requests from untrusted peers, making it particularly dangerous in environments where external devices can be connected without proper authentication mechanisms. This issue aligns with ATT&CK technique T1068 by enabling local privilege escalation through kernel memory corruption and T1547 by potentially compromising system integrity through device driver vulnerabilities.
The mitigation strategy involves implementing comprehensive packet size validation throughout the XDomain processing pipeline by plumbing the actual packet length parameter through the xdomain_request_work function. This approach ensures that each typecast operation occurs only after verifying that the allocated buffer contains sufficient data to accommodate the target protocol structure. The fix requires adding explicit size checks against known struct sizes before any memory casting operations, effectively preventing the out-of-bounds reads that characterize this vulnerability. Additionally, implementing proper input sanitization and bounds checking mechanisms aligns with security best practices outlined in the Linux kernel security documentation and helps prevent similar classes of vulnerabilities from manifesting in other subsystems.