CVE-2026-98859

Received Received - Intake

Use-After-Free in Linux Kernel HID Multitouch Driver

Publication date: 2026-10-18

Last updated on: 2026-10-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: HID: multitouch: stop the release timer from being rearmed on remove mt_remove() quiesces the sticky-finger timer before stopping the hardware: timer_delete_sync(&td->release_timer); sysfs_remove_group(&hdev->dev.kobj, &mt_attribute_group); hid_hw_stop(hdev); timer_delete_sync() waits for a running callback and dequeues the timer, but it does not stop the timer from being armed again. The transport is still delivering reports at that point, and the report path rearms it: if (app->quirks & MT_QUIRK_STICKY_FINGERS) { if (td->mt_io_flags & MT_IO_SLOTS_MASK) mod_timer(&td->release_timer, jiffies + msecs_to_jiffies(100)); A report that arrives after timer_delete_sync() has returned therefore leaves the timer queued. td is allocated with devm_kzalloc() against hdev->dev, so it is freed when the driver is unbound, after mt_remove() returns. When the timer fires afterwards, mt_expired_timeout() dereferences the freed td: struct mt_device *td = timer_container_of(td, t, release_timer); struct hid_device *hdev = td->hdev; if (test_and_set_bit_lock(MT_IO_FLAGS_RUNNING, &td->mt_io_flags)) Simply moving the teardown after hid_hw_stop() does not fix this on its own, because mt_expired_timeout() calls mt_release_contacts(), which walks hdev->inputs; the timer still has to be quiesced before hid_hw_stop() tears the input devices down. Use timer_shutdown_sync() instead, which additionally makes any later mod_timer() a no-op, so neither ordering constraint has to be traded off against the other. This is the final-teardown pattern the function was introduced for, and hid-wiimote already uses it for the same reason.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-10-18

Last Modified

2026-10-19

Generated

2026-10-19

AI Q&A

2026-10-18

EPSS Evaluated

N/A

NVD

CVE-2026-98859

EUVD

EUVD-2026-103799

Affected Vendors & Products

Vendor	Product	Version / Range
Linux	Linux	4f4001bc76fd1a138a501fbd3d68cce72cbf96ce
Linux	Linux	4f4001bc76fd1a138a501fbd3d68cce72cbf96ce
Linux	Linux	4f4001bc76fd1a138a501fbd3d68cce72cbf96ce
Linux	Linux	4f4001bc76fd1a138a501fbd3d68cce72cbf96ce
Linux	Linux	4.13

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a use-after-free issue in the HID multitouch driver. The problem occurs when the release timer is rearmed after being deleted during device removal, leading to a timer firing after the associated memory is freed. This causes a crash when the timer callback tries to access freed memory.

Detection Guidance

This vulnerability is specific to the Linux kernel's HID multitouch driver and cannot be detected via network scans or generic commands. It requires kernel-level inspection to identify the affected driver and timer management issues. Check kernel logs for hid-multitouch related errors or warnings.

Impact Analysis

This vulnerability could cause system crashes or instability when a multitouch device is disconnected or the driver is unloaded. It may lead to kernel panics or unexpected behavior in systems using affected HID multitouch devices.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA as it is a Linux kernel issue related to hardware input handling. Compliance impacts would depend on system-specific configurations and usage.

Mitigation Strategies

Update the Linux kernel to a patched version that includes the fix for CVE-2026-98859. The patch replaces timer_delete_sync() with timer_shutdown_sync() in the hid-multitouch driver to prevent timer rearms after teardown.

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