CVE-2026-56936 in Android
Summary
by MITRE • 10/06/2026
In wacom_hid_set_device_mode of wacom_sys.c, there is a possible out-of-bounds write due to a missing bounds check. This could lead to physical escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability identified in the Linux kernel's Wacom HID driver presents a critical security risk stemming from an insufficient validation mechanism within the wacom_hid_set_device_mode function located in the wacom_sys.c source file. This flaw constitutes a classic out-of-bounds write condition, where the software fails to verify that data being written to memory falls within the allocated boundaries of the target buffer or structure. In the context of operating system kernels, such errors are particularly severe because they allow for direct manipulation of kernel memory space without requiring user interaction or specific application privileges. The absence of a bounds check means that an attacker can supply crafted input parameters that exceed the expected limits, causing data to be written past the end of the intended variable into adjacent memory regions. This type of flaw is formally categorized under CWE-787: Out-of-bounds Write in standard vulnerability classification systems, which highlights the fundamental failure to enforce boundary constraints during memory operations.
The operational impact of this vulnerability extends far beyond simple data corruption or application crashes. Because the affected code resides within the kernel space and involves device mode configuration for Wacom input devices such as tablets and styluses, successful exploitation can lead to a physical escalation of privilege. This means that an attacker who has access to the system's hardware interface or can trigger specific HID events may execute arbitrary code with root-level privileges. The severity is compounded by the fact that no additional execution privileges are required for exploitation, nor does it rely on user interaction such as clicking a malicious link or opening a file. An adversary could potentially exploit this flaw through automated scripts or physical access to inject malformed reports via the USB or Bluetooth interface of connected Wacom devices. This aligns with ATT&CK technique T1059: Command and Scripting Interpreter, specifically when used for privilege escalation, as well as techniques related to hardware-based attacks like those described in T1207: Rogue Access Point if physical access is leveraged to spoof device identity or inject malicious HID reports.
From a technical perspective, the wacom_hid_set_device_mode function is responsible for configuring various operational modes of Wacom devices based on incoming data from the host system. When this function processes input without validating indices or lengths against predefined limits, it creates an exploitable window where memory corruption occurs. The kernel's strict separation between user space and kernel space is bypassed because the vulnerability allows writing to arbitrary kernel addresses. This can be used to overwrite critical control structures such as function pointers, return addresses on the stack, or security-critical variables like credentials or capability flags. By carefully crafting the out-of-bounds write, an attacker can achieve code execution in ring 0, effectively gaining full control over the operating system. The lack of user interaction requirement makes this vulnerability particularly dangerous in environments where devices are constantly connected and auto-configuration is enabled, as it reduces the attack surface to mere physical or logical proximity to the vulnerable driver.
Mitigation strategies for this vulnerability must focus on both immediate patching and long-term defensive coding practices. The primary remediation involves applying vendor-provided kernel updates that include a fix for wacom_sys.c, ensuring that all array indices and buffer lengths are rigorously validated before memory access occurs. Developers should implement strict bounds checking routines that compare input values against the maximum allowable size of the target data structures. Additionally, enabling Kernel Hardening features such as KASLR (Kernel Address Space Layout Randomization) can mitigate exploitation by making it harder for attackers to predict memory addresses needed for successful code execution. Using stack protectors and enforcing stricter type safety in C programming within kernel modules further reduces the likelihood of similar out-of-bounds errors. System administrators should also monitor for unusual HID device connections or unexpected privilege changes, as these may indicate attempted exploitation attempts. Regular security audits focusing on input validation in driver-level code are essential to prevent recurrence of such critical flaws that compromise system integrity and confidentiality.