CVE-2026-31729

Analyzed Analyzed - Analysis Complete

Out-of-Bounds Access in Linux Kernel USB Type-C UCSI

Publication date: 2026-05-01

Last updated on: 2026-05-07

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: usb: typec: ucsi: validate connector number in ucsi_notify_common() The connector number extracted from CCI via UCSI_CCI_CONNECTOR() is a 7-bit field (0-127) that is used to index into the connector array in ucsi_connector_change(). However, the array is only allocated for the number of connectors reported by the device (typically 2-4 entries). A malicious or malfunctioning device could report an out-of-range connector number in the CCI, causing an out-of-bounds array access in ucsi_connector_change(). Add a bounds check in ucsi_notify_common(), the central point where CCI is parsed after arriving from hardware, so that bogus connector numbers are rejected before they propagate further.

CVSS Scores

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Meta Information

Published

2026-05-01

Last Modified

2026-05-07

Generated

2026-07-06

AI Q&A

2026-05-01

EPSS Evaluated

2026-07-05

NVD

CVE-2026-31729

EUVD

EUVD-2026-26542

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	From 6.13 (inc) to 6.18.22 (exc)
linux	linux_kernel	From 6.19 (inc) to 6.19.12 (exc)
linux	linux_kernel	From 5.5 (inc) to 6.12.81 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-129	The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.

Attack-Flow Graph

Executive Summary

This vulnerability exists in the Linux kernel's USB Type-C subsystem, specifically in the ucsi_notify_common() function. The issue arises because the connector number extracted from the device's CCI (Connector Capability Information) is a 7-bit value (0-127), but the kernel only allocates an array sized for the actual number of connectors reported by the device, usually between 2 and 4.

A malicious or malfunctioning device can report a connector number that is out of the valid range, causing the kernel to perform an out-of-bounds array access in the ucsi_connector_change() function. This can lead to undefined behavior or potential security issues.

The vulnerability was fixed by adding a bounds check in ucsi_notify_common() to reject invalid connector numbers before they are processed further.

Impact Analysis

If exploited, this vulnerability could allow a malicious or malfunctioning USB Type-C device to cause the Linux kernel to access memory outside the bounds of an allocated array. This out-of-bounds access could lead to system instability, crashes, or potentially allow an attacker to execute arbitrary code or escalate privileges.

The impact depends on the specific system and how it handles such memory errors, but it generally poses a risk to system reliability and security when connecting untrusted USB Type-C devices.

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