CVE-2026-64248

Name of the Vulnerable Software and Affected Versions Linux kernel versions 6.1 through 6.18.33

Description An issue exists in the MIPS architecture implementation where the smp send stop() function parks secondary CPUs in stop this cpu(). While the function marks the CPU as offline for the scheduler using set cpu online(false), it fails to notify the Read-Copy-Update (RCU) mechanism. Consequently, RCU continues to wait for a quiescent state from CPUs that are spinning with interrupts disabled. When irq work sync() is called during the reboot or shutdown path, it triggers synchronize rcu() on architectures lacking an irq work self-IPI, such as MIPS. This leads to a deadlock where the system blocks on a grace period that can never complete, resulting in a hung reboot. This behavior was specifically observed on Realtek MIPS switch SoCs using MIPS interAptiv.

Recommendations Update the Linux kernel to version 6.18.34 or later, or apply the backported patch for versions as old as 6.1. As a temporary mitigation, avoid triggering irq work sync() in the reboot or shutdown path on affected MIPS systems until the update is applied.