# CVE-2026-93689: WinFsp null pointer dereference in kernel device control handler

Source: https://junglewise.ai/threats/cve-2026-93689-winfsp-through-2-2-26215-contains-a-null-pointer-dereference  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-93689 · Severity: medium · CVSS 5.5 · Published 2026-09-18

WinFsp is a Windows file system proxy that allows FUSE-based file systems to run on Windows. An unprivileged local user can crash the system by exploiting a null pointer vulnerability in the kernel driver's device control handler, causing a denial of service.

Technologies: [WinFSP](https://junglewise.ai/threats/technologies/winfsp). Vendors: [WinFSP](https://junglewise.ai/threats/vendors/winfsp).

## Quick answers

**Is CVE-2026-93689 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-93689 being exploited in the wild.

**How severe is CVE-2026-93689?** Medium severity, with a CVSS score of 5.5, published 18 September 2026.

**Which products and versions are affected?** WinFSP through 2.2.26215.

**Is there a fix for CVE-2026-93689?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-93689 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-93689?** Check whether you run WinFSP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a null pointer dereference in the Fast I/O device control handler of the WinFsp kernel driver, where the volume context is not validated before use. An attacker with local access can trigger this by opening the WinFsp control device and issuing FSP_IOCTL_TRANSACT requests, resulting in a kernel crash.

## Affected products

- WinFsp WinFsp through 2.2.26215

## Timeline

- 2026-09-18: disclosed

## References

- [https://github.com/winfsp/winfsp](https://github.com/winfsp/winfsp)
- [https://github.com/winfsp/winfsp/blob/v2.2B4/src/sys/devctl.c](https://github.com/winfsp/winfsp/blob/v2.2B4/src/sys/devctl.c)

## Related threats

- [WinFsp integer overflow privilege escalation](https://junglewise.ai/threats/cve-2026-7162-winfsp-integer-overflow-privilege-escalation)
- [WinFSP local privilege escalation via kernel heap overflow](https://junglewise.ai/threats/cve-2026-3006-winfsp-local-privilege-escalation-via-kernel-heap-overflow)