CVE-2026-89460 Linux CVE debrief

Who should care

Linux system administrators and users who utilize the 'perf stat' command with CPU hotplug events should assess their exposure to this vulnerability. Defenders should prioritize updating the Linux kernel to the latest version and monitoring system logs for potential crashes.

Why it matters

The Linux kernel vulnerability CVE-2026-89460 can cause system crashes when using the 'perf stat' command with CPU hotplug events. Linux system administrators and users should assess their exposure and prioritize updating the Linux kernel to the latest version.

• System crashes due to NULL pointer dereference
• Potential data loss or corruption due to system crashes
• Increased risk of denial-of-service (DoS) attacks
• Need for Linux kernel updates and monitoring

Technical summary

The Linux kernel vulnerability CVE-2026-89460 is caused by the dynamic allocation of per-CPU event infrastructure during event creation. When CPUs are hotplug added during a 'perf stat' command run, the kernel crashes due to a NULL pointer dereference. The issue is resolved by introducing a CPU hotplug prepare/dead callback pair that creates and removes per-CPU counter data while the CPU is offline.

Defensive priority

Medium

Recommended defensive actions

• Review and update Linux kernel to the latest version
• Monitor system logs for potential crashes
• Implement compensating controls for CPU hotplug events
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance

Evidence notes

The issue is triggered when using the 'perf stat' command with CPU hotplug events. The root cause is the dynamic allocation of struct cpu_cf_events at first event initialization, which does not account for CPUs that may be offline during event creation and become online during the perf run time.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.