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.
| Software | Affected versions |
|---|---|
| linux / linux_kernel | >= 5.10.246, < 5.10.261 |
| linux / linux_kernel | >= 5.15.196, < 5.15.212 |
| linux / linux_kernel | >= 6.1.158, < 6.1.178 |
| linux / linux_kernel | >= 6.6.114, < 6.6.145 |
| linux / linux_kernel | >= 6.12.55, < 6.12.97 |
| linux / linux_kernel | >= 6.17.5, < 6.18 |
| linux / linux_kernel | >= 6.18.1, < 6.18.39 |
| linux / linux_kernel | >= 6.19, < 7.1.4 |
| linux / linux_kernel | = 6.18 |
| linux / linux_kernel | = 6.18-rc2 |
| linux / linux_kernel | = 6.18-rc3 |
| linux / linux_kernel | = 6.18-rc4 |
| linux / linux_kernel | = 6.18-rc5 |
| linux / linux_kernel | = 6.18-rc6 |
| linux / linux_kernel | = 6.18-rc7 |
| linux / linux_kernel | = 7.2-rc1 |
| linux / linux_kernel | = 7.2-rc2 |
A vulnerability database tells you what is broken. Attack surface management tells you where it is running: it discovers your internet-facing assets and flags the ones affected by issues like this one.
What is attack surface management? →A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
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Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
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