CVE-2026-64373: cpufreq: Fix hotplug-suspend race during reboot

Severity: medium (CVSS 4.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-25 · updated 2026-09-08
Weakness: CWE-362

Description

In the Linux kernel, the following vulnerability has been resolved: cpufreq: Fix hotplug-suspend race during reboot During system reboot, cpufreq_suspend() is called via the kernel_restart() -> device_shutdown() path. Unlike the normal system suspend path, the reboot path does not call freeze_processes(), so userspace processes and kernel threads remain active. This allows CPU hotplug operations to run concurrently with cpufreq_suspend(). The original code has no synchronization with CPU hotplug, leading to a race condition where governor_data can be freed by the hotplug path while cpufreq_suspend() is still accessing it, resulting in a null pointer dereference: Unable to handle kernel NULL pointer dereference Call Trace: do_kernel_fault+0x28/0x3c cpufreq_suspend+0xdc/0x160 device_shutdown+0x18/0x200 kernel_restart+0x40/0x80 arm64_sys_reboot+0x1b0/0x200 Fix this by adding cpus_read_lock()/cpus_read_unlock() to cpufreq_suspend() to block CPU hotplug operations while suspend is in progress. [ rjw: Changelog edits ]

Affected products

Linux kernel: from 4.4.198 before 4.5; from 4.9.198 before 4.10; from 4.14.151 before 4.15; from 4.19.81 before 4.20; from 5.3.8 before 5.4; from 5.4.1 before 5.10.261 — fixed in 4.10, 4.15, 4.20, 4.5, 5.10.261, 5.15.212

How to fix

Upgrade to a fixed version: Linux kernel 4.10, 4.15, 4.20, 4.5. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-64373 or the next vulnerability affects your stack