Microsoft · Ancillary Function Driver (afd.sys)
CVE-2011-2005
Microsoft Ancillary Function Driver (afd.sys) Improper Input Validation Vulnerability
What it is
afd.sys in the Ancillary Function Driver in Microsoft Windows XP SP2 and SP3 and Server 2003 SP2 does not properly validate user-mode input passed to kernel mode, which allows local users to gain privileges via a crafted application, aka "Ancillary Function Driver Elevation of Privilege Vulnerability."
CISA: afd.sys in the Ancillary Function Driver in Microsoft Windows does not properly validate user-mode input passed to kernel mode, which allows local users to gain privileges via a crafted application.
What to do
Apply updates per vendor instructions.
Deadline for US federal agencies: April 18, 2022
More exploited flaws from Microsoft
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Oct 13, 2026 | Command Injection | Windows | High 8.8 | 9.8% |
| Sep 25, 2026 | Code Injection | SharePoint | High 8.8 | 8.2% |
| Sep 8, 2026 | Link Following | Windows | High 7.8 | 0.4% |
| Sep 8, 2026 | Heap-Based Buffer Overflow | Windows | High 7.8 | 0.4% |
| Aug 26, 2026 | Remote Code Execution | SQL Server | High 8.8 | 57% |
| Aug 18, 2026 | Double Free | Internet Key Exchange (IKE) Service Extensions | Critical 9.8 | 77% |
| Aug 18, 2026 | Weak Authentication | SharePoint | Critical 9.1 | 70% |
| Aug 11, 2026 | Windows Ancillary Function Driver for WinSock Use-After-Free | Windows Ancillary Function Driver for WinSock | High 7.0 | 0.3% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.