CVE-2026-41088: Microsoft Windows WinSock Ancillary Function Driver type confusion

CVE-2026-41088 · Severity: high · CVSS 7.8 · Published 2026-05-12

A security vulnerability exists in a core Windows networking component responsible for handling socket connections. An attacker who already has basic access to a computer could exploit this flaw to gain full administrative control over the system. This could allow them to bypass security restrictions, access sensitive data, or install malicious software.

Technologies: Microsoft Windows 11, Microsoft Windows Ancillary Function Driver for WinSock, Microsoft Windows 10, Microsoft Windows Server 2022, Microsoft Windows Server 2025. Vendors: Microsoft.

Quick answers

Is CVE-2026-41088 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-41088 being exploited in the wild.
How severe is CVE-2026-41088?
High severity, with a CVSS score of 7.8, published 12 May 2026.
Which products and versions are affected?
Microsoft Windows 11 23H2, 24H2, 25H2, 26H1; Microsoft Windows 10 21H2, 22H2; Microsoft Windows Server 2022 Standard, 23H2; Microsoft Windows Server 2025 All versions.
Is there a fix for CVE-2026-41088?
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-2026-41088 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2026-41088?
Check whether you run Microsoft Windows 11, Microsoft Windows Ancillary Function Driver for WinSock, Microsoft Windows 10 or one of the others listed 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

A type confusion vulnerability exists in the Windows Ancillary Function Driver (afd.sys), which serves as the kernel-mode interface for WinSock. The flaw stems from the driver incorrectly processing resources using incompatible types, or potentially through external control of file paths during socket operations. An attacker with low-privileged local access can exploit this by sending specially crafted I/O control (IOCTL) requests to the driver. Successful exploitation allows the attacker to execute code with SYSTEM privileges, effectively gaining full control of the affected host. Microsoft has released security updates to address this issue across supported versions of Windows and Windows Server.

Affected products

  • Microsoft Windows 10 21H2, 22H2
  • Microsoft Windows 11 23H2, 24H2, 25H2, 26H1
  • Microsoft Windows Server 2022 Standard, 23H2
  • Microsoft Windows Server 2025 All versions

Timeline

  • 2026-05-12: disclosed
  • 2026-05-12: advisory

References

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