In the Linux kernel for MIPS architectures, the function stop_this_cpu parks secondary CPUs and marks them offline, but the kernel fails to notify the RCU subsystem that these CPUs are dying. During a reboot or shutdown, irq_work_sync calls synchronize_rcu and waits for a grace period that can never complete because RCU is still waiting on the parked CPUs. This causes the system to hang at shutdown, effectively denying service. The weakness is a missing status report leading to a synchronization bug.

The flaw manifests in all 6.18.x kernels before 6.18.34 and in earlier 6.1.x kernels lacking the backport. Systems running those kernels on MIPS CPUs, such as Realtek MIPS switch SoCs, are affected.

The EPSS score is below 1 %, indicating a low likelihood of exploitation, and the vulnerability is not listed in the CISA KEV catalog. The CVSS score of 5.5 reflects moderate severity. Exploitation requires privileged access to trigger a reboot or shutdown, an assumption that is inferred from the need to initiate a system reboot; it is likely not remotely exploitable. If an attacker can force the device to reboot, the failure to report dying CPUs will cause the system to hang during shutdown, preventing normal recovery. Overall risk remains low to moderate, but the denial‑of‑service impact warrants prompt patching.