CVE-2026-64013 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
ACPI: button: Fix ACPI GPE handler leak during removal
Commit a7e23ec17fee ("ACPI: button: Install notifier for system events as well") changed the ACPI notify handler type for ACPI buttons to ACPI_ALL_NOTIFY, but it forgot to update acpi_button_remove() to reflect that change. This leads to leaking the notify handler past driver removal, which may cause a kernel crash to occur if ACPI notify on the given device is triggered after removing the driver, and causes a subsequent probe of the given device with the same driver to fail.
Address this by updating the acpi_remove_notify_handler() call in acpi_button_remove() as appropriate.
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Analysis
by VulDB Data Team • 07/19/2026
This vulnerability exists within the Linux kernel's ACPI button subsystem where a memory management issue occurs during driver removal operations. The problem stems from an incomplete code modification in commit a7e23ec17fee which altered how ACPI notify handlers are installed for button devices by changing the handler type from a specific notification class to ACPI_ALL_NOTIFY. This change was implemented to capture system events more comprehensively but introduced a critical oversight in the driver cleanup routine. When the acpi_button_remove() function executes, it fails to properly unregister the notify handler that was installed with the new ACPI_ALL_NOTIFY type, creating a persistent reference to the removed driver components.
The technical flaw represents a classic resource leak pattern where kernel notification handlers remain registered even after their associated driver modules have been unloaded from memory. This occurs because the removal function continues to use the old acpi_remove_notify_handler() call format that was appropriate for the previous handler type but is incompatible with the new ACPI_ALL_NOTIFY registration method. The consequence of this oversight creates a dangling reference scenario where the kernel maintains pointers to memory locations that may have been deallocated or repurposed during driver removal, leading to potential dereference operations on invalid memory addresses.
The operational impact of this vulnerability manifests as system instability and potential kernel crashes when ACPI button devices trigger notifications after their drivers have been removed. This condition is particularly dangerous because it can occur during normal system operations such as device hot-plugging, power management transitions, or system shutdown sequences where the kernel expects clean driver removals. When an ACPI notification event occurs on a device whose handler has not been properly unregistered, the kernel attempts to execute code from memory locations that may no longer contain valid handler routines, resulting in page faults or general protection faults that can crash the entire system.
The vulnerability directly relates to CWE-404, which describes improper resource management where allocated resources are not properly released, and aligns with ATT&CK technique T1547.001 for registry modification and T1059.006 for command and scripting interpreter usage in exploitation scenarios. This flaw can be exploited by attackers who understand the kernel's ACPI subsystem behavior to trigger specific device removal and reinsertion sequences that force the system into a crash state. The proper mitigation involves updating the acpi_button_remove() function to use the correct acpi_remove_notify_handler() API call format that matches the handler registration type used in the modified code path, ensuring complete cleanup of all notification handler references during driver unloading operations.
The fix requires careful attention to API compatibility and proper cleanup sequence implementation within the kernel's ACPI subsystem. System administrators should ensure their kernels are updated with patches containing the corrected acpi_button_remove() function that properly handles all types of ACPI notify handlers regardless of how they were initially registered. This vulnerability highlights the importance of thorough testing during kernel modifications, particularly in subsystems where resource management and notification handling intersect, as seemingly minor API changes can have significant implications for system stability and security posture.