# CVE-2026-80626: powerpc/perf: fix preempt count underflow in fsl_emb_pmu_del

> A local attacker can trigger a preempt count underflow in the PowerPC performance monitor driver, causing a kernel bug and 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:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** BELL-CVE-2026-80626, DEBIAN-CVE-2026-80626, GHSA-j46p-7hmv-qpv9, UBUNTU-CVE-2026-80626

## What is CVE-2026-80626?

CVE-2026-80626 is a 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:

powerpc/perf: fix preempt count underflow in fsl_emb_pmu_del

fsl_emb_pmu_del() unconditionally calls put_cpu_var(cpu_hw_events) at
the 'out:' label, but only calls the matching get_cpu_var() after the
'i < 0' early-return check. When event->hw.idx is negative the
function jumps to 'out:' without having taken get_cpu_var(), and the
trailing put_cpu_var() then issues an unmatched preempt_enable(),
underflowing preempt_count.

On a CONFIG_PREEMPT=y kernel preempt_count would underflow and
eventually present as a 'scheduling while atomic' BUG.

Move put_cpu_var() to pair with get_cpu_var() so the percpu access is
correctly bracketed and the 'out:' label only handles perf_pmu_enable.

## Which versions are affected by CVE-2026-80626?


## How do I fix CVE-2026-80626?

Apply the vendor's patch.

## Is CVE-2026-80626 being exploited?

There is no known exploitation of CVE-2026-80626 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80626 and fix it if it is affected.

What it is: CVE-2026-80626 is a 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.
Exploitation: There is no known exploitation of CVE-2026-80626 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-2026-80626/ (Markdown: https://insights.sbomify.com/CVE-2026-80626/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80626
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80626
- OSV: https://osv.dev/vulnerability/CVE-2026-80626

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80626/
Summaries are generated and may contain mistakes; the official description above is the record.