CVE-2026-64014: Linux Kernel Information Disclosure Flaw

CVE-2026-64014 Overview

CVE-2026-64014 is an out-of-bounds read vulnerability in the Linux kernel's usbtouchscreen input driver, specifically in the nexio_read_data() function used to parse NEXIO touchscreen interrupt packets. The driver reads data_len and x_len fields from a packed big-endian 16-bit header supplied by the USB device without validating them against the URB transfer buffer size. A malicious or malfunctioning USB device can declare oversized lengths and cause the driver to read up to roughly 64 KiB beyond the coherent DMA allocation. Kernel memory contents leak to userspace as ABS_X / ABS_Y touch coordinate events, and far-reaching reads can hit unmapped pages and trigger a fault.

Critical Impact
A USB device that lies about its length fields can leak adjacent kernel memory to userspace via touch events or crash the kernel by reading unmapped pages.

Affected Products

Linux kernel drivers/input/touchscreen/usbtouchscreen.c NEXIO device support
Multiple stable Linux kernel branches (fix backported across eight kernel commits)
Systems that permit USB touchscreen devices, including physically accessible endpoints and virtual machines with USB passthrough

Discovery Timeline

2026-07-19 - CVE-2026-64014 published to NVD
2026-07-19 - Last updated in NVD database

Technical Details for CVE-2026-64014

Vulnerability Analysis

The nexio_read_data() callback in drivers/input/touchscreen/usbtouchscreen.c extracts data_len and x_len from a packed __be16 header inside the device's interrupt packet. It then walks packet->data[0..x_len) and packet->data[x_len..data_len), comparing each byte against NEXIO_THRESHOLD to derive begin_x and begin_y touch coordinates.

Both length fields are 16-bit wire values with a maximum of 65535. The existing adjustments only shave at most 0x100 / 0x80 off, leaving the loop bound near 0xfeff. The URB transfer buffer allocated via usb_alloc_coherent() is only rept_size (1024) bytes, with the first 7 bytes consumed by the packed header. This leaves packet->data[] with 1017 valid bytes. The read_data() callbacks are not passed urb->actual_length, so no other bound constrains the walk.

The first index whose byte exceeds the threshold is assigned into begin_x or begin_y and forwarded into the reported touch coordinates. Adjacent kernel memory therefore leaks to userspace through input events. The fix clamps data_len to the buffer's data[] capacity and x_len to data_len.

Root Cause

The root cause is missing input validation [CWE-125] on attacker-controlled length fields received from a USB device. The driver trusts device-supplied data_len and x_len values without comparing them to the actual URB buffer capacity.

Attack Vector

An attacker with the ability to attach a crafted USB device, either through physical access or via USB passthrough in a virtualization context, presents a NEXIO-compatible interface with malicious header length fields. The kernel driver then reads out-of-bounds memory and either exposes those bytes to userspace as coordinate values or crashes on an unmapped page.

No verified public exploit code is available. Refer to the Linux Kernel Commit 0ca809e and Linux Kernel Commit 45c829e for the authoritative patch diffs describing the clamping logic.

Detection Methods for CVE-2026-64014

Indicators of Compromise

Unexpected NEXIO USB touchscreen device attachments logged by udev or dmesg on systems that do not use touchscreens.
Kernel oops or page fault entries referencing nexio_read_data or usbtouchscreen in kernel logs.
Anomalous ABS_X / ABS_Y input event streams with values inconsistent with real touch input from /dev/input/event*.

Detection Strategies

Audit loaded kernel modules for usbtouchscreen on hosts where touch input is not required and flag its presence.
Correlate USB device enumeration events with subsequent kernel warnings or crashes involving the input subsystem.
Monitor for kernel version strings that pre-date the fix commits listed in the NVD references.

Monitoring Recommendations

Forward dmesg and journalctl -k output to a centralized logging platform and alert on usbtouchscreen or nexio strings.
Track USB VID:PID enumeration on servers and workstations, alerting on unexpected HID or touchscreen classes.
Baseline kernel package versions across the fleet and flag hosts running unpatched kernels.

How to Mitigate CVE-2026-64014

Immediate Actions Required

Apply the vendor kernel update that includes commits 0ca809e, 103d2de, 2905281, 45c829e, 7585b6a, 95f4733, d883312, and e7cdcb2 for your stable branch.
Blacklist the usbtouchscreen module on systems that do not require touchscreen input.
Restrict physical USB access on servers and enforce USB device allow-lists on endpoints.

Patch Information

The upstream fix clamps data_len to the size of packet->data[] and clamps x_len to the sanitized data_len before the byte-scan loop. Backports are available across multiple stable trees. See the reference commits including Linux Kernel Commit 0ca809e, Linux Kernel Commit 103d2de, Linux Kernel Commit 2905281, Linux Kernel Commit 45c829e, Linux Kernel Commit 7585b6a, Linux Kernel Commit 95f4733, Linux Kernel Commit d883312, and Linux Kernel Commit e7cdcb2.

Workarounds

Blacklist the module using /etc/modprobe.d/blacklist-usbtouchscreen.conf with blacklist usbtouchscreen and rebuild the initramfs.
Deploy USBGuard or equivalent policies to deny unauthorized HID/touchscreen devices from binding.
Disable USB passthrough for untrusted virtual machines until the host kernel is patched.

bash

# Blacklist the vulnerable driver until the kernel is patched
echo "blacklist usbtouchscreen" | sudo tee /etc/modprobe.d/blacklist-usbtouchscreen.conf
sudo update-initramfs -u

# Verify the module is not loaded
lsmod | grep usbtouchscreen