Microsoft · Security update · May 12, 2026
KB5087544: May 2026 cumulative update for Windows 10 21H2
KB5087544, released May 12, 2026, fixes 54 CVEs across 3 products. None of them is reported as exploited. Patch Radar priority: Urgent.
Urgent
CVEs closed
54
3 rated Critical
Exploited
0
None reported
Exploitation more likely
7
Microsoft's assessment
Highest EPSS
0.0267
85th percentile
Priority of the 54 CVEs
Patch now 0
Urgent 10
High 36
Routine 8
Applies to
| Product |
|---|
| Windows 10 Version 21H2 for 32-bit Systems |
| Windows 10 Version 21H2 for ARM64-based Systems |
| Windows 10 Version 21H2 for x64-based Systems |
CVEs this fix closes
| Priority | CVE | Component | Impact | CVSS | EPSS | Exploitation |
|---|---|---|---|---|---|---|
| Urgent | CVE-2026-40398 | Windows Remote Desktop | Elevation of Privilege | 7.8 | 0.0267 | More likely |
| Urgent | CVE-2026-33835 | Windows Cloud Files Mini Filter Driver | Elevation of Privilege | 7.8 | 0.0212 | More likely |
| Urgent | CVE-2026-33837 | Windows TCP/IP | Elevation of Privilege | 7.8 | 0.0184 | More likely |
| Urgent | CVE-2026-35416 | Windows Ancillary Function Driver for WinSock | Elevation of Privilege | 7.0 | 0.0165 | More likely |
| Urgent | CVE-2026-35421 | Windows GDI | Remote Code Execution | 7.8 | 0.0053 | Exploitation Unlikely |
| Urgent | CVE-2026-40403 | Windows Win32K - GRFX | Remote Code Execution | 8.8 | 0.0043 | Exploitation Less Likely |
| Urgent | CVE-2026-35417 | Windows Win32K - ICOMP | Elevation of Privilege | 7.8 | 0.0035 | More likely |
| Urgent | CVE-2026-33841 | Windows Kernel | Elevation of Privilege | 7.8 | 0.0031 | More likely |
| Urgent | CVE-2026-32161 | Windows Native WiFi Miniport Driver | Remote Code Execution | 7.5 | 0.0030 | Exploitation Less Likely |
| Urgent | CVE-2026-40397 | Windows Common Log File System Driver | Elevation of Privilege | 7.8 | 0.0027 | More likely |
| High | CVE-2026-35424 | Windows Internet Key Exchange (IKE) Protocol | Denial of Service | 7.5 | 0.0119 | Exploitation Unlikely |
| High | CVE-2026-40406 | Windows TCP/IP | Information Disclosure | 7.5 | 0.0093 | Exploitation Less Likely |
| High | CVE-2026-40415 | Windows TCP/IP | Remote Code Execution | 8.1 | 0.0079 | Exploitation Unlikely |
| High | CVE-2026-40414 | Windows TCP/IP | Denial of Service | 7.4 | 0.0053 | Exploitation Unlikely |
| High | CVE-2026-34329 | Windows Message Queuing | Remote Code Execution | 8.8 | 0.0046 | Exploitation Less Likely |
| High | CVE-2026-40413 | Windows TCP/IP | Denial of Service | 7.4 | 0.0040 | Exploitation Less Likely |
| High | CVE-2026-33838 | Windows Message Queuing | Elevation of Privilege | 7.8 | 0.0040 | Exploitation Less Likely |
| High | CVE-2026-35415 | Windows Storage Spaces Controller | Elevation of Privilege | 7.8 | 0.0033 | Exploitation Less Likely |
| High | CVE-2026-40401 | Windows TCP/IP | Denial of Service | 7.1 | 0.0033 | Exploitation Unlikely |
| High | CVE-2026-40399 | Windows TCP/IP | Elevation of Privilege | 7.8 | 0.0033 | Exploitation Less Likely |
| High | CVE-2026-34343 | Windows Application Identity (AppID) Subsystem | Elevation of Privilege | 7.8 | 0.0033 | Exploitation Less Likely |
| High | CVE-2026-41088 | Windows Ancillary Function Driver for WinSock | Elevation of Privilege | 7.8 | 0.0032 | Exploitation Unlikely |
| High | CVE-2026-34344 | Windows Ancillary Function Driver for WinSock | Elevation of Privilege | 7.8 | 0.0031 | Exploitation Less Likely |
| High | CVE-2026-34330 | Windows Win32K - GRFX | Elevation of Privilege | 7.8 | 0.0030 | Exploitation Unlikely |
| High | CVE-2026-40377 | Windows Cryptographic Services | Elevation of Privilege | 7.8 | 0.0030 | Exploitation Less Likely |
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