What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-18 · updated 2026-09-22
• Weakness: CWE-476

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.

Affected products

• winfsp: through 2.2.26215

References

• https://github.com/winfsp/winfsp
• https://github.com/winfsp/winfsp/blob/v2.2B4/src/sys/devctl.c#L105-L114
• https://github.com/winfsp/winfsp/blob/v2.2B4/src/sys/devctl.c#L146-L152
• https://github.com/winfsp/winfsp/blob/v2.2B4/src/sys/devctl.c#L68-L73
• https://github.com/winfsp/winfsp/blob/v2.2B4/src/sys/volume.c#L1059-L1060
• https://github.com/winfsp/winfsp/commit/b8103265ec63fa87ac264c62bb796dbc38376652
• https://github.com/winfsp/winfsp/releases/tag/v2.2B4
• https://www.vulncheck.com/advisories/winfsp-through-2.2.26215-null-pointer-dereference-via-fast-i-o

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