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CVE-2026-64183: Linux Kernel: EFI Workqueue Allocation Issue
CVE-2026-64183
CVE-2026-64183
Summary
A bug in the Linux kernel's EFI system could cause it to crash when accessing firmware settings. This bug affects systems that use EFI firmware. To fix this issue, the kernel developers have rearranged the order in which some initialization tasks are performed. If you're using the Linux kernel, it's recommended to update to the latest version to ensure you have the fix.
What to do
No fix is available yet. Check with your software vendor for updates.
Affected software
| Vendor | Product | Affected versions |
|---|---|---|
| linux | linux |
< 29cd94e678fcb3c4fd0f359deeac6d61334323fc 6.6 |
Original title
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 PR...
Original 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.
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.
- https://git.kernel.org/stable/c/29cd94e678fcb3c4fd0f359deeac6d61334323fc
- https://git.kernel.org/stable/c/6996e954ae830f5b793ba6cf449885ca519dbdd2
- https://git.kernel.org/stable/c/c32a1fbe0f9a48453a552bb315cc4f1e7a74084e
- https://git.kernel.org/stable/c/e871549f7894ad4114b3dd53f241aa25a268ba8b
- https://git.kernel.org/stable/c/13c6da02e767152c9ac4330962247a5e47011035
Published: 19 Jul 2026 · Updated: 19 Jul 2026 · First seen: 19 Jul 2026