CVE-2025-71119 powerpc/kexec: Enable SMT before waking offline CPUs
A kernel warning occurs during kexec on PowerPC when SMT is disabled, potentially causing instability or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-71119?
CVE-2025-71119 is a medium-severity denial of service vulnerability in Linux kernel, published on 14 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
powerpc/kexec: Enable SMT before waking offline CPUs
If SMT is disabled or a partial SMT state is enabled, when a new kernel image is loaded for kexec, on reboot the following warning is observed:
kexec: Waking offline cpu 228. WARNING: CPU: 0 PID: 9062 at arch/powerpc/kexec/core_64.c:223 kexec_prepare_cpus+0x1b0/0x1bc [snip] NIP kexec_prepare_cpus+0x1b0/0x1bc LR kexec_prepare_cpus+0x1a0/0x1bc Call Trace: kexec_prepare_cpus+0x1a0/0x1bc (unreliable) default_machine_kexec+0x160/0x19c machine_kexec+0x80/0x88 kernel_kexec+0xd0/0x118 __do_sys_reboot+0x210/0x2c4 system_call_exception+0x124/0x320 system_call_vectored_common+0x15c/0x2ec
This occurs as add_cpu() fails due to cpu_bootable() returning false for CPUs that fail the cpu_smt_thread_allowed() check or non primary threads if SMT is disabled.
Fix the issue by enabling SMT and resetting the number of SMT threads to the number of threads per core, before attempting to wake up all present CPUs.
Which versions are affected by CVE-2025-71119?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-71119?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-71119 being exploited?
There is no known exploitation of CVE-2025-71119 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-71119, DEBIAN-CVE-2025-71119, GHSA-c6m6-8r45-fwg7, ROOT-OS-UBUNTU-2404-CVE-2025-71119, UBUNTU-CVE-2025-71119.