CVE-2026-64014 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
Input: usbtouchscreen - clamp NEXIO data_len/x_len to URB buffer size
nexio_read_data() pulls data_len and x_len from a packed __be16 header in the device's interrupt packet and then walks packet->data[0..x_len)
and packet->data[x_len..data_len) comparing each byte against a
threshold.
Both fields are 16-bit on the wire (max 65535). The existing adjustments shave at most 0x100 / 0x80 off, so the loop bound can still reach roughly 0xfeff. The URB transfer buffer for NEXIO is rept_size (1024) bytes from usb_alloc_coherent(), with the first 7 occupied by the packed header — so packet->data[] has 1017 valid bytes. read_data()
callbacks are not given urb->actual_length, and nothing else bounds the walk.
A device that lies about its length can get a ~64 KiB out-of-bounds read past the coherent DMA allocation. The first index whose byte exceeds NEXIO_THRESHOLD lands in begin_x / begin_y and from there into the reported touch coordinates, so adjacent kernel memory contents leak to userspace as ABS_X / ABS_Y events. Far enough out, the read can also hit an unmapped page and fault.
Fix this all by clamping data_len to the buffer's data[] capacity and
x_len to data_len.
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Analysis
by VulDB Data Team • 07/19/2026
The vulnerability in question affects the Linux kernel's usb touch screen driver specifically targeting the nexio protocol implementation. This issue stems from inadequate input validation within the nexio_read_data() function which processes interrupt packets from usb touch devices. The function extracts two 16-bit fields data_len and x_len from a packed __be16 header located in the device's interrupt packet structure. These values are subsequently used as loop bounds to traverse through packet->data[] array segments, creating a potential for out-of-bounds memory access conditions.
The technical flaw manifests when a malicious or faulty usb touch device provides incorrect length values in its protocol headers. While the kernel does perform some adjustments by subtracting at most 0x100/0x80 from these values, the resulting loop bounds can still reach approximately 0xfeff bytes. The underlying URB transfer buffer for NEXIO devices is allocated with rept_size (1024) bytes through usb_alloc_coherent() function calls, but the first 7 bytes are reserved for the packed header, leaving only 1017 valid bytes available in packet->data[]. Since read_data() callbacks do not receive urb->actual_length information and no additional bounds checking is performed, the kernel processes data beyond the allocated buffer boundaries.
This vulnerability falls under CWE-129 Input Validation and is classified as an out-of-bounds read condition that can lead to information disclosure and system instability. The operational impact includes potential kernel memory leakage to userspace through ABS_X/ABS_Y event reporting mechanisms, where adjacent kernel memory contents are exposed as touch coordinates. In more severe cases, when the out-of-bounds access reaches unmapped memory pages, it can cause kernel faults and system crashes. The ATT&CK framework would categorize this as a privilege escalation technique through device driver manipulation, potentially enabling an attacker to extract sensitive kernel information or cause denial of service conditions.
The fix implementation involves proper input clamping mechanisms that restrict data_len to the actual buffer capacity available in packet->data[] array and ensure x_len does not exceed data_len. This defensive programming approach prevents malicious devices from exploiting the vulnerability by providing oversized length values that would otherwise cause memory access violations. The solution aligns with secure coding practices recommended for kernel space development, specifically addressing buffer overflow prevention and input validation requirements. This patch demonstrates proper bounds checking implementation that protects against malformed device protocol data while maintaining compatibility with legitimate touch screen devices operating within expected parameter ranges.