CVE-2026-80611 ACPI: processor_idle: Mark LPI enter functions as __cpuidle
Enabling function tracing or Kprobes on Linux kernels can trigger RCU warnings during idle entry, potentially causing system instability or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80611?
CVE-2026-80611 is a denial of service vulnerability in Linux, published on 28 Aug 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:
ACPI: processor_idle: Mark LPI enter functions as __cpuidle
When function tracing or Kprobes is enabled, entering an ACPI Low Power Idle (LPI) state triggers the following RCU splat:
RCU not on for: acpi_idle_lpi_enter+0x4/0xd8 WARNING: CPU: 8 PID: 0 at include/linux/trace_recursion.h:162 function_trace_call+0x1e8/0x228
The acpi_idle_lpi_enter() function is invoked within the cpuidle path after RCU has already been disabled for the current local CPU. Consequently, ftrace's function_trace_call() expects RCU to be actively watching before recording trace data, emitting a warning if it is not.
Fix this by annotating acpi_idle_lpi_enter(), the generic __weak stub, and the RISC-V implementation of acpi_processor_ffh_lpi_enter() with __cpuidle. This moves these functions into the '.cpuidle.text' section, implicitly disabling ftrace instrumentation (notrace) along this sensitive path and preventing trace-induced RCU warnings during idle entry.
Which versions are affected by CVE-2026-80611?
How do I fix CVE-2026-80611?
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-2026-80611 being exploited?
There is no known exploitation of CVE-2026-80611 in the wild and no public exploit code.
Sources
Also known as AZL-98063, BELL-CVE-2026-80611, DEBIAN-CVE-2026-80611, GHSA-vvhc-p9vw-ph6p, UBUNTU-CVE-2026-80611.