CVE-2026-93826 in Linux
Summary
by MITRE • 09/24/2026
In the Linux kernel, the following vulnerability has been resolved:
HID: hidpp: fix potential UAF in hidpp_connect_event()
If input_register_device() fails, we call input_free_device(), but keep stale pointer to the old device in hidpp->input, which could potentially lead to UAF. Fix that by resetting it to NULL before returning from hidpp_connect_event().
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/24/2026
The vulnerability identified within the Linux kernel's Human Interface Device (HID) subsystem specifically targets the hidpp driver, which manages devices using Logitech's proprietary wireless protocol known as HID++10 or HID++. This flaw manifests during the device initialization phase in the hidpp_connect_event function. The core technical issue is a use-after-free condition arising from improper pointer management when input registration fails. Under normal operation, the kernel attempts to register an input device with the subsystem via input_register_device(). If this call succeeds, the driver proceeds normally. However, if it returns an error code indicating failure, the current implementation invokes input_free_device() to release the memory associated with that failed allocation. Crucially, while the memory is freed, the hidpp structure retains a stale pointer in its input field pointing to the now-deallocated object. This creates a dangling reference that remains accessible within the driver's state until it is explicitly cleared or overwritten by subsequent operations.
The operational impact of this vulnerability centers on potential system instability and security risks associated with use-after-free conditions. Although immediate exploitation may be difficult due to the specific context of device connection events, which are typically triggered during hardware insertion or initialization, the presence of a dangling pointer allows for memory corruption if that freed memory is reallocated and accessed later by other kernel components or drivers. An attacker who can influence the timing of device connections or manipulate system memory allocation patterns might exploit this race condition to execute arbitrary code with kernel privileges. This represents a significant security risk as it bypasses standard user-space isolation boundaries, potentially leading to full system compromise. The vulnerability is classified under CWE-416, which denotes use-after-free errors, highlighting the failure to properly manage object lifecycles and pointer validity after deallocation.
From an offensive security perspective, this flaw aligns with techniques observed in advanced persistent threats that seek to escalate privileges by exploiting kernel memory corruption bugs. It relates to ATT&CK technique T1055, which covers process injection and other forms of code execution within the operating system environment via exploitation of software vulnerabilities. The specific mechanism here relies on manipulating the state of a driver during its initialization sequence, making it relevant to supply chain or hardware-based attack vectors where physical access or controlled peripheral insertion is possible. Mitigation strategies primarily involve applying the upstream kernel patch that addresses this issue by ensuring the hidpp->input pointer is set to NULL immediately after input_free_device() is called in error paths. System administrators should ensure their Linux kernels are updated to versions containing this fix, particularly for systems using Logitech HID++ devices such as wireless mice and keyboards. Additionally, enabling Kernel Address Sanitizer (KASAN) during development or testing phases can help detect similar dangling pointer issues early in the software lifecycle by tracking memory accesses after free events.