CVE-2026-23158 in Linux
Summary
by MITRE • 02/14/2026
In the Linux kernel, the following vulnerability has been resolved:
gpio: virtuser: fix UAF in configfs release path
The gpio-virtuser configfs release path uses guard(mutex) to protect the device structure. However, the device is freed before the guard cleanup runs, causing mutex_unlock() to operate on freed memory.
Specifically, gpio_virtuser_device_config_group_release() destroys the mutex and frees the device while still inside the guard(mutex) scope. When the function returns, the guard cleanup invokes mutex_unlock(&dev->lock), resulting in a slab use-after-free.
Limit the mutex lifetime by using a scoped_guard() only around the activation check, so that the lock is released before mutex_destroy() and kfree() are called.
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Analysis
by VulDB Data Team • 05/05/2026
The vulnerability identified as CVE-2026-23158 represents a critical use-after-free condition within the Linux kernel's gpio-virtuser subsystem, specifically affecting the configfs release path implementation. This flaw manifests in the gpio-virtuser device management code where improper synchronization mechanisms lead to memory corruption during device destruction. The vulnerability resides in the gpio_virtuser_device_config_group_release() function which handles the cleanup process for virtual gpio devices exposed through configfs interface, creating a scenario where memory safety is compromised during normal device teardown operations.
The technical root cause stems from improper mutex lifecycle management within the device release path. The implementation employs a guard(mutex) mechanism to protect access to the device structure during cleanup operations, but this protection is fundamentally flawed. During the release process, the device structure is freed before the guard cleanup routine executes, specifically when mutex_unlock() is called on a mutex that has already been destroyed. This sequence creates a classic use-after-free scenario where the kernel attempts to unlock a mutex that references freed memory, leading to potential memory corruption and system instability. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in memory management.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling privilege escalation and system compromise within kernel space. When the mutex_unlock() operation attempts to access freed memory, it can trigger undefined behavior that may be exploitable by malicious actors with kernel-level access or through carefully crafted attack vectors. The vulnerability affects systems utilizing the gpio-virtuser subsystem through configfs interface, which is commonly deployed in virtualized environments and embedded systems where virtual gpio devices are managed programmatically. This flaw particularly impacts systems running kernel versions where the gpio-virtuser driver is active and configfs-based device management is utilized, creating a potential attack surface for kernel exploits.
Mitigation strategies should focus on correcting the mutex lifecycle management within the gpio-virtuser subsystem by implementing proper scoped_guard() usage that limits mutex lifetime to only the necessary activation check period. The fix requires restructuring the release path to ensure that mutex destruction and memory deallocation occur after the guard cleanup has completed, preventing the scenario where mutex_unlock() operates on freed memory. System administrators should prioritize kernel updates that include the specific patch addressing this vulnerability, while security teams should monitor for potential exploitation attempts in environments utilizing virtual gpio device management. The solution follows established best practices for kernel memory management and synchronization, ensuring proper resource cleanup order and preventing similar issues in other subsystems that may exhibit similar mutex lifecycle management flaws. This vulnerability demonstrates the importance of careful synchronization primitive usage in kernel space, where improper resource management can lead to critical security implications affecting system integrity and stability.