CVE-2026-93181: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: perf/x86/intel/uncore: Fix uncore_box ref/unref ordering In uncore_event_cpu_online(), uncore_box_ref() was called before uncore_change_context(). uncore_box_ref() gates on box->cpu >= 0, but box->cpu is still -1 at that point because uncore_change_context() has not run yet. As a result, the box is never initialized on the first CPU to come online in a die, leaving it permanently uninitialized in the single-CPU-per-die case. Thus, box->refcnt is one count below the true value, and in the CPU offline path, the box will be torn down on the second-to-last CPU. In uncore_event_cpu_offline(), uncore_box_unref() was called after uncore_change_context(), so box->cpu is already -1 when the collector CPU goes offline, which prevents it from tearing down the box. Fix by swapping the call order in both paths so that uncore_box_{ref,unref}() runs at the point where box->cpu reflects the correct context. Move allocate_boxes() out of uncore_box_ref() to enable this reordering.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= c74443d92f68f07c03ae242ced554b749e6c6736, < 64aa1bb4017d598828c6d8cd718f43daf2a83375; >= c74443d92f68f07c03ae242ced554b749e6c6736, < 174f0582e38abe03b88e15f04bfe58490f88cb19
Linux	Linux	6.11

References

Timeline

Published: Sep 17, 2026
Last Modified: Sep 17, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-93181?

In the Linux kernel, the following vulnerability has been resolved: perf/x86/intel/uncore: Fix uncore_box ref/unref ordering In uncore_event_cpu_online(), uncore_box_ref() was called before uncore_change_context(). uncore_box_ref() gates on box->cpu >= 0, but box->cpu is still -1 at that point because uncore_change_context() has not run yet. As a result, the box is never initialized on the first CPU to come online in a die, leaving it permanently uninitialized in the single-CPU-per-die case. Thus, box->refcnt is one count below the true value, and in the CPU offline path, the box will be torn down on the second-to-last CPU. In uncore_event_cpu_offline(), uncore_box_unref() was called after uncore_change_context(), so box->cpu is already -1 when the collector CPU goes offline, which prevents it from tearing down the box. Fix by swapping the call order in both paths so that uncore_box_{ref,unref}() runs at the point where box->cpu reflects the correct context. Move allocate_boxes() out of uncore_box_ref() to enable this reordering.

How severe is CVE-2026-93181?

Severity scoring for CVE-2026-93181 is pending analysis.

How do I fix CVE-2026-93181?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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