CVE-2026-64014

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 devices 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 buffers data[] capacity and x_len to data_len.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/0ca809ea8e0355299266c46e5f1755040aa8dcf3
• https://git.kernel.org/stable/c/103d2de9f505f56da173e43f12dba62f92620278
• https://git.kernel.org/stable/c/2905281cbda52ec9df540113b35b835feb5fafd3
• https://git.kernel.org/stable/c/45c829e5eb3b974282bae50b7cca2cc891f74f0b
• https://git.kernel.org/stable/c/7585b6aa55d8ac85ad22f522e1059f93507727b6
• https://git.kernel.org/stable/c/95f47331dfde243f93e679ce70bd0c24b37c683d
• https://git.kernel.org/stable/c/d883312061ccde8c536595998aaf687ec070077c
• https://git.kernel.org/stable/c/e7cdcb266ba06d8480809b78ab8bb2bf8ff51ccb