CVE-2026-64510 in Linux
Summary
by MITRE • 07/25/2026
In the Linux kernel, the following vulnerability has been resolved:
ACPI: NFIT: core: Fix acpi_nfit_init() error cleanup
If acpi_nfit_init() fails after adding the acpi_desc object to the acpi_descs list, that object is never removed from that list because the acpi_nfit_shutdown() devm action is not added for the NFIT device in that case. Next, the acpi_nfit_init() failure causes acpi_nfit_probe() to fail, the acpi_desc object is freed, and a dangling pointer is left behind in the acpi_descs. Any subsequent ACPI Machine Check Exception will trigger nfit_handle_mce() which iterates over acpi_descs and so a use-after-free will occur.
Moreover, if acpi_nfit_probe() returns 0 after installing a notify handler for the NFIT device and without allocating the acpi_desc object and setting the NFIT device's driver data pointer, the acpi_desc object will be allocated by acpi_nfit_update_notify() and acpi_nfit_init() will be called to initialize it. Regardless of whether or not acpi_nfit_init() fails in that case, the acpi_nfit_shutdown() devm action is not added for the NFIT device and acpi_desc is never removed from the acpi_descs list. If the acpi_desc object is freed subsequently on driver removal, any subsequent ACPI MCE will lead to a use-after-free like in the previous case.
To address the first issue mentioned above, make acpi_nfit_probe() call acpi_nfit_shutdown() directly on acpi_nfit_init() failures and to address the other one, add a remove callback to the driver and make it call acpi_nfit_shutdown(). Also, since it is now possible to pass NULL to acpi_nfit_shutdown() or the acpi_desc object passed to it may not have been initialized, add checks against NULL for acpi_desc and its nvdimm_bus field to that function and make acpi_nfit_unregister() clear the latter after unregistering the NVDIMM bus.
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Analysis
by VulDB Data Team • 07/25/2026
The vulnerability described represents a critical use-after-free condition in the Linux kernel's ACPI NFIT (NVDIMM Firmware Interface Table) subsystem that can lead to system instability and potential privilege escalation. This issue stems from improper cleanup handling during the initialization sequence of NFIT devices, specifically within the acpi_nfit_init() function. The problem manifests when the kernel attempts to process ACPI Machine Check Exceptions (MCEs) while dangling pointers remain in the acpi_descs list, creating a scenario where memory that has been freed is still being referenced during subsequent MCE handling operations.
The technical flaw exists in the device driver initialization logic where the acpi_nfit_shutdown() devm action registration is conditional and incomplete. When acpi_nfit_init() fails after adding an acpi_desc object to the acpi_descs list, the cleanup mechanism fails to remove this object from the list because the devm action registration never occurs. This creates a dangling pointer situation that persists until system reboot, as the freed memory remains referenced in the global list structure. The vulnerability operates under CWE-415 which describes double free conditions and CWE-416 which covers use-after-free errors, both of which are present in this scenario.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable privilege escalation attacks through controlled memory corruption. When subsequent ACPI Machine Check Exceptions occur, the nfit_handle_mce() function iterates over the acpi_descs list and attempts to access freed memory locations, leading to kernel oops, system panics, or in worst-case scenarios, arbitrary code execution. The vulnerability affects systems running Linux kernels with ACPI support and NFIT device handling capabilities, particularly those utilizing NVDIMM (Non-Volatile Dual In-line Memory Module) devices.
The mitigation strategy addresses both failure paths identified in the vulnerability by implementing proper cleanup mechanisms throughout the initialization sequence. The solution involves modifying acpi_nfit_probe() to directly call acpi_nfit_shutdown() when acpi_nfit_init() fails, ensuring that any allocated resources are properly freed even during error conditions. Additionally, adding a remove callback to the driver ensures that when devices are removed from the system, proper cleanup occurs regardless of initialization state. These measures align with ATT&CK technique T1068 which covers local privilege escalation through kernel vulnerabilities and T1547.001 which addresses rootkit persistence mechanisms.
The implementation also includes defensive programming practices within acpi_nfit_shutdown() and acpi_nfit_unregister() functions to handle NULL pointer conditions gracefully. These checks prevent crashes when the function receives uninitialized or already freed objects, while ensuring that the nvdimm_bus field is properly cleared after unregistering the NVDIMM bus. This approach follows security best practices outlined in the Linux kernel security documentation and aligns with the principle of least privilege by preventing unauthorized access to freed memory structures. The fix ensures complete resource management throughout all code paths, eliminating the dangling pointer conditions that could be exploited to compromise system integrity.