Executive brief
A vulnerability in the Linux kernel's handling of processor interrupt controllers can cause systems to hang or become unresponsive when waking up from sleep mode (suspend-to-RAM). This occurs because the computer's firmware may re-enable a high-performance interrupt mode (x2apic) that the operating system had previously disabled, leading to a communication mismatch. This issue primarily affects physical hardware and can lead to a complete loss of system availability after a sleep cycle.
Technical details
A vulnerability in the x86 APIC (Advanced Programmable Interrupt Controller) management in the Linux kernel leads to a system hang during resume from suspend-to-RAM (S3). During the boot process, the kernel may disable x2apic mode if IRQ remapping is unsupported; however, upon resume, system firmware may re-enable x2apic mode as part of its restoration of the initial boot configuration (per ACPI v6.6 specs). This creates a state where the hardware is in x2apic mode while the kernel continues to use the legacy xapic interface. The fix involves updating lapic_resume() to explicitly disable x2apic if the kernel's internal state (x2apic_mode) indicates it should be disabled. This issue affects bare-metal x86 systems using standard configurations.
Affected products
- Linux Linux kernel All versions prior to the fix
Timeline
- 2026-03-06: other: Initial patch authored
- 2026-03-19: patched: Patch committed to stable tree
- 2026-05-08: disclosed: CVE published
References
- https://git.kernel.org/stable/c/11712c4eb384098db4cb08792e223c818b908c1a
- https://git.kernel.org/stable/c/1a85f84214f9d790216547ac6086bf8033cd9e5a
- https://git.kernel.org/stable/c/1d8440c1e7c49715f937416ac90cf260f1f1712c
- https://git.kernel.org/stable/c/3dd0812a7c764cd8f3b0182441ac22da0a7f3b09
- https://git.kernel.org/stable/c/8cc7dd77a1466f0ec58c03478b2e735a5b289b96
- https://git.kernel.org/stable/c/965289b120cc68cca886c75219c68b8c15751d73
- https://git.kernel.org/stable/c/a6ad6f2e31b524cbb66b2f370bad0cf17d327e6c