CVE-2026-64183
Received Received - Intake

EFI Runtime Workqueue Allocation Fix in Linux Kernel

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: efi: Allocate runtime workqueue before ACPI init Since commit 5894cf571e14 ("acpi/prmt: Use EFI runtime sandbox to invoke PRM handlers") ACPI PRM calls are delegated to a workqueue which runs in a kernel thread, making it easier to detect and mitigate faulting memory accesses performed by the firmware. Rafael reports that such PRM accesses may occur before efisubsys_init() executes, which is where the workqueue is allocated, leading to NULL pointer dereferences. Since acpi_init() [which triggers the early PRM accesses] executes as a subsys_initcall() as well, and has its own dependencies that may be sensitive to initcall ordering, deferring acpi_init() is not an option. So instead, split off the workqueue allocation into its own postcore initcall, as this is the only missing piece to allow EFI runtime calls to be made. This ensures that EFI runtime call (including PRM calls) are accessible to all code running at subsys_initcall() level.

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-64183
EUVD
EUVD-2026-45868

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
linux linux_kernel *
linux_kernel linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a NULL pointer dereference issue. It occurs because ACPI PRM calls may happen before the EFI runtime workqueue is allocated, leading to crashes when firmware tries to access memory during early system initialization.

Detection Guidance

This vulnerability is specific to the Linux kernel and involves a NULL pointer dereference due to early ACPI PRM calls before EFI runtime workqueue allocation. Detection requires checking kernel logs for NULL pointer dereference errors or kernel panics related to ACPI or EFI subsystems.

Impact Analysis

This could cause system instability or crashes during boot if firmware attempts to use EFI runtime services before the kernel is fully initialized. Users might experience unexpected reboots or kernel panics.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA. It is a Linux kernel issue involving NULL pointer dereferences due to improper workqueue allocation timing, which could lead to system instability or crashes but does not inherently impact data protection or privacy compliance requirements.

Mitigation Strategies

Apply the kernel patch that allocates the EFI runtime workqueue before ACPI initialization. Update to a Linux kernel version that includes the fix from commit 5894cf571e14 or later. Monitor kernel logs for ACPI or EFI-related errors as a sign of exploitation or misconfiguration.

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