NULL pointer dereference in Winfsp
CVE-2026-93689
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.002 (4.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 4.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
Weakness classification (CWE)
References
- github.com/winfsp/winfsp/commit/b8103265ec63fa87ac264c62bb796dbc38376652 (patch)
- github.com/winfsp/winfsp (product)
- github.com/winfsp/winfsp/blob/v2.2B4/src/sys/devctl.c (technical-description)
- github.com/winfsp/winfsp/blob/v2.2B4/src/sys/devctl.c (technical-description)
- github.com/winfsp/winfsp/blob/v2.2B4/src/sys/devctl.c (technical-description)
- github.com/winfsp/winfsp/blob/v2.2B4/src/sys/volume.c (technical-description)
- github.com/winfsp/winfsp/releases/tag/v2.2B4 (release-notes)
- www.vulncheck.com/advisories/winfsp-through-2.2.26215-null-pointer-dereference-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-93689?
- CVE-2026-93689 is a medium-severity vulnerability in Winfsp, classified under NULL Pointer Dereference. CVSS score: 5.5/10. Published 2026-09-18.
- How severe is CVE-2026-93689?
- Medium severity. CVSS v3 base score is 5.5 out of 10.