---
id: CVE-2026-64364
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  HID: multitouch: fix out-of-bounds bit access on mt_io_flags

  mt_io_flags is a single unsigned long, but mt_process_slot(),
  mt_release_pending_palms() and mt_release_co…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  HID: multitouch: fix out-of-bounds bit access on mt_io_flags

  mt_io_flags is a single unsigned long, but mt_process_slot(),
  mt_release_pending_palms() and mt_release_co…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-125
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.10.246, < 5.10.261'
  - 'linux_kernel >= 5.15.196, < 5.15.212'
  - 'linux_kernel >= 6.1.158, < 6.1.178'
  - 'linux_kernel >= 6.6.114, < 6.6.145'
  - 'linux_kernel >= 6.12.55, < 6.12.97'
  - 'linux_kernel >= 6.17.5, < 6.18'
  - 'linux_kernel >= 6.18.1, < 6.18.39'
  - 'linux_kernel >= 6.19, < 7.1.4'
  - linux_kernel = 6.18
  - linux_kernel = 7.2
patched:
  - linux_kernel 7.1.4
published: '2026-07-25'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T21:35:45.760'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64364'
references:
  - url: 'https://git.kernel.org/stable/c/12e90656e330ff8bbaf2f29c535fdb8a11cc6f55'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/152983d87387f6a8ae72b73474cfa55fbcf1ec75'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/37daa8c96bd563d03150e23f094cb60703594a6d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6493ebf9489efef0105078377b973ab33d51af22'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8813b0612275cc61fe9e6603d0ee019247ade6be'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a6d5ce2e1a2d7bf189bde8a659d04b65f0b0725d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b5c037d6b807017e74a115288f81bc9cd5a5aab8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e24918ee67c4dc3d20d4670750e46e9b160365f4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00354
epssPercentile: 0.26373
ingestedAt: '2026-07-27T06:16:50.734Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

HID: multitouch: fix out-of-bounds bit access on mt_io_flags

mt_io_flags is a single unsigned long, but mt_process_slot(),
mt_release_pending_palms() and mt_release_contacts() use it as a
per-slot bitmap indexed by the slot number. That slot number is only
bounded by td->maxcontacts, which is taken from the device's
ContactCountMaximum feature report and can be up to 255, not by
BITS_PER_LONG.

As a result, a multitouch device that advertises a large contact count
makes set_bit()/clear_bit() operate past the mt_io_flags word and
corrupt the adjacent members of struct mt_device. The sticky-fingers
release timer is the easiest way to reach this. mt_release_contacts()
runs

	for (i = 0; i < mt->num_slots; i++)
		clear_bit(i, &td->mt_io_flags);

with num_slots == maxcontacts. For maxcontacts around 250 the loop
clears the bits that overlap td->applications.next, zeroing that list
head, and the list_for_each_entry() that immediately follows then
dereferences NULL. The kernel panics from timer (softirq) context. On a
KASAN build this shows up as a general protection fault in
mt_release_contacts() with a null-ptr-deref at offset 0x58, which is
offsetof(struct mt_application, num_received).

The state is reachable from an untrusted USB or Bluetooth HID
multitouch device; no local privileges are required.

Store the per-slot active state in a separately allocated bitmap sized
for maxcontacts, the same pattern already used for pending_palm_slots,
and keep only MT_IO_FLAGS_RUNNING in mt_io_flags. The two
"mt_io_flags & MT_IO_SLOTS_MASK" arming checks become
bitmap_empty(td->active_slots, td->maxcontacts).

Move MT_IO_FLAGS_RUNNING back to bit 0. It was bumped to bit 32 by the
same commit to leave the low byte for the slot bits; with the slot bits
gone it fits in bit 0 again, which also keeps it within the unsigned
long on 32-bit.

## Affected

- `linux_kernel >= 5.10.246, < 5.10.261`
- `linux_kernel >= 5.15.196, < 5.15.212`
- `linux_kernel >= 6.1.158, < 6.1.178`
- `linux_kernel >= 6.6.114, < 6.6.145`
- `linux_kernel >= 6.12.55, < 6.12.97`
- `linux_kernel >= 6.17.5, < 6.18`
- `linux_kernel >= 6.18.1, < 6.18.39`
- `linux_kernel >= 6.19, < 7.1.4`
- `linux_kernel = 6.18`
- `linux_kernel = 7.2`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.1.4`