# CVE-2025-40359: perf/x86/intel: Fix KASAN global-out-of-bounds warning

> A local attacker can trigger a kernel out-of-bounds read in the Intel perf subsystem, potentially causing a system crash or denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-40359, DEBIAN-CVE-2025-40359, GHSA-4mfx-236h-48h4, UBUNTU-CVE-2025-40359

## What is CVE-2025-40359?

CVE-2025-40359 is a memory corruption vulnerability in Linux, published on 16 Dec 2025. 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:

perf/x86/intel: Fix KASAN global-out-of-bounds warning

When running "perf mem record" command on CWF, the below KASAN
global-out-of-bounds warning is seen.

  ==================================================================
  BUG: KASAN: global-out-of-bounds in cmt_latency_data+0x176/0x1b0
  Read of size 4 at addr ffffffffb721d000 by task dtlb/9850

  Call Trace:

   kasan_report+0xb8/0xf0
   cmt_latency_data+0x176/0x1b0
   setup_arch_pebs_sample_data+0xf49/0x2560
   intel_pmu_drain_arch_pebs+0x577/0xb00
   handle_pmi_common+0x6c4/0xc80

The issue is caused by below code in __grt_latency_data(). The code
tries to access x86_hybrid_pmu structure which doesn't exist on
non-hybrid platform like CWF.

        WARN_ON_ONCE(hybrid_pmu(event->pmu)->pmu_type == hybrid_big)

So add is_hybrid() check before calling this WARN_ON_ONCE to fix the
global-out-of-bounds access issue.

## Which versions are affected by CVE-2025-40359?


## How do I fix CVE-2025-40359?

Apply the vendor's patch.

## Is CVE-2025-40359 being exploited?

There is no known exploitation of CVE-2025-40359 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40359 and fix it if it is affected.

What it is: CVE-2025-40359 is a memory corruption vulnerability in Linux, published on 16 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-40359 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-40359/ (Markdown: https://insights.sbomify.com/CVE-2025-40359/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40359
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40359
- OSV: https://osv.dev/vulnerability/CVE-2025-40359

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40359/
Summaries are generated and may contain mistakes; the official description above is the record.