# CVE-2026-93689: WinFsp through 2.2.26215 NULL Pointer Dereference via Fast I/O

> An unprivileged local user can cause a system crash by triggering a null pointer dereference in the WinFsp kernel driver's Fast I/O handler.

- **Severity:** Medium 6.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **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:** No
- **Published:** 18 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-grx3-v6wv-8gq8

## What is CVE-2026-93689?

CVE-2026-93689 is a medium-severity vulnerability in winfsp, published on 18 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

WinFsp through 2.2.26215 contains a null pointer dereference vulnerability in the kernel driver's Fast I/O device control handler that fails to validate the volume context before use. An unprivileged local user can trigger a denial of service by opening the WinFsp control device and issuing FSP_IOCTL_TRANSACT requests, causing a system crash.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-93689?


## How do I fix CVE-2026-93689?

No fix has been published for CVE-2026-93689 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-93689 being exploited?

There is no known exploitation of CVE-2026-93689 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93689 and fix it if it is affected.

What it is: CVE-2026-93689 is a medium-severity vulnerability in winfsp, published on 18 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-2026-93689 in the wild and no public exploit code.

Affected product: winfsp. 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-2026-93689/ (Markdown: https://insights.sbomify.com/CVE-2026-93689/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93689
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93689
- OSV: https://osv.dev/vulnerability/CVE-2026-93689

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93689/
Summaries are generated and may contain mistakes; the official description above is the record.