Concurrent execution using shared resource with improper synchronization ('race condition') in Windows TCP/IP allows an authorized attacker to elevate privileges locally.
The following code is for security research and authorized testing only.
python
import ctypes
import threading
import time
# Conceptual Proof of Concept for Race Condition in Windows TCP/IP
# Note: This is a structural demonstration. Actual exploitation requires specific IOCTLs and memory layout.
def vulnerability_thread():
"""Simulates the first thread accessing the shared resource."""
try:
# In a real scenario, this would invoke a specific vulnerable syscall or IOCTL
print("[Thread 1] Starting resource access...")
time.sleep(0.001) # Introduce a tiny delay to widen the race window
print("[Thread 1] Resource check passed.")
except Exception as e:
print(f"Error in thread 1: {e}")
def exploit_thread():
"""Simulates the second thread modifying the shared resource."""
try:
# This thread attempts to modify the state before Thread 1 commits
while True:
# Busy wait or precise timing to hit the race window
pass
print("[Thread 2] Resource modified!")
except Exception as e:
print(f"Error in thread 2: {e}")
if __name__ == "__main__":
print("Starting PoC for CVE-2026-27921...")
t1 = threading.Thread(target=vulnerability_thread)
t2 = threading.Thread(target=exploit_thread)
t1.start()
# Slight offset to encourage the race condition
time.sleep(0.0005)
t2.start()
t1.join()
t2.join()
print("Exploit attempt finished.")