In the Linux kernel, the following vulnerability has been resolved: irqchip/gic-v5: Immediately exec priority drop following activate With GICv5 an… (CVE-2026-98878)

The Linux kernel's GICv5 driver previously performed the priority drop (via the GIC CDEOI instruction) only during irq_eoi(), which coincides with interrupt deactivation. Because all interrupts have the same priority, no new interrupts of equal or lower priority can be signaled until a priority drop occurs. If a long-running process or a guest VM holds an active interrupt, this delayed priority drop blocks other interrupts, effectively causing a denial of service. The fix moves the priority drop to immediately after interrupt acknowledgment in the main GICv5 interrupt handler, ensuring new interrupts can be signaled promptly. Interrupt deactivation remains part of irq_eoi(), preventing the same interrupt from being signaled twice without software deactivation.

This vulnerability can cause a denial of service by blocking all other interrupts while a long-running process or VM holds an active interrupt, due to delayed priority dropping in the GICv5 interrupt controller driver. This affects system responsiveness and interrupt handling reliability.

A fix has been implemented in the Linux kernel to move the priority drop to immediately after interrupt acknowledgment in the GICv5 driver. Users should update to the fixed kernel version once available. No other mitigation steps are indicated.