# CVE-2026-89604: efivarfs: Rate limit statfs() handler

> Unprivileged local users can cause a denial of service by flooding the efivarfs statfs handler, triggering expensive SMM operations on x86 systems.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100856, BELL-CVE-2026-89604, DEBIAN-CVE-2026-89604, GHSA-pmmg-3c8m-93q3, UBUNTU-CVE-2026-89604

## What is CVE-2026-89604?

CVE-2026-89604 is a denial of service vulnerability in Linux, published on 11 Sep 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:

efivarfs: Rate limit statfs() handler

Ravi reports that statfs() may be called by unprivileged users on the
efivarfs mount point, which may result in a flood of calls to the
QueryVariableInfo() runtime service. These calls are disproportionately
costly on x86 systems where the variable store is backed by SMM, as each
SMM entry requires a rendez-vous of all the CPUs.

So rate limit the calls to QueryVariableInfo() at twice per second, and
return the most recently obtained value for calls that are elided.

## Which versions are affected by CVE-2026-89604?


## How do I fix CVE-2026-89604?

Apply the vendor's patch.

## Is CVE-2026-89604 being exploited?

There is no known exploitation of CVE-2026-89604 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89604 and fix it if it is affected.

What it is: CVE-2026-89604 is a denial of service vulnerability in Linux, published on 11 Sep 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-2026-89604 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-2026-89604/ (Markdown: https://insights.sbomify.com/CVE-2026-89604/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89604
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89604
- OSV: https://osv.dev/vulnerability/CVE-2026-89604

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89604/
Summaries are generated and may contain mistakes; the official description above is the record.