CVE-2026-63959

Received Received - Intake

USB Type-C TCPM Stack Buffer Overflow in Linux Kernel

Publication date: 2026-07-19

Last updated on: 2026-07-20

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: usb: typec: tcpm/tcpci_maxim: validate header NDO against RX_BYTE_CNT A broken/malicious port can transmit a CRC-valid frame whose header advertises up to seven data objects but whose body carries fewer than that. Check for this, and rightfully reject the message, instead of reading from uninitialized stack memory.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-07-19

Last Modified

2026-07-20

Generated

2026-07-20

AI Q&A

2026-07-19

EPSS Evaluated

N/A

NVD

CVE-2026-63959

EUVD

EUVD-2026-45732

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a flaw in the USB Type-C port manager (tcpm) and Maxim TCPM implementation. A malicious or broken port can send a valid CRC frame where the header claims up to seven data objects but the actual data contains fewer. This mismatch can cause the system to read uninitialized stack memory when processing the frame.

Detection Guidance

This vulnerability involves malformed USB Type-C Power Delivery (PD) messages. Detection requires monitoring kernel logs for Type-C PD protocol errors or unexpected frame headers. Check dmesg for errors like 'invalid NDO count' or 'RX_BYTE_CNT mismatch'. Use 'dmesg | grep -i typec' or 'journalctl -k | grep -i typec' to inspect logs for Type-C PD stack warnings.

Impact Analysis

This vulnerability could allow an attacker with physical access to a USB Type-C port to potentially read sensitive data from system memory. It may lead to information disclosure or system instability if exploited.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards as it is a low-level kernel issue related to USB Type-C protocol handling. Compliance impacts would depend on system-specific implementations rather than this vulnerability itself.

Mitigation Strategies

Update the Linux kernel to the latest stable version where this fix is included. If immediate patching is not possible, disable USB Type-C PD functionality if not required, or restrict untrusted USB-C ports via physical controls or software policies until the kernel is updated.

Hi! I’m here to help you understand CVE-2026-63959. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70