CVE-2025-20206: Cisco Secure Client DLL Hijacking RCE

CVE-2025-20206 Overview

A vulnerability in the interprocess communication (IPC) channel of Cisco Secure Client for Windows could allow an authenticated, local attacker to perform a DLL hijacking attack on an affected device if the Secure Firewall Posture Engine, formerly HostScan, is installed. This vulnerability arises due to insufficient validation of resources loaded by the application.

Critical Impact

This vulnerability could allow arbitrary code execution with SYSTEM privileges.

Affected Products

• Cisco Secure Client
• Microsoft Windows

Discovery Timeline

• Not Available - Vulnerability discovered by Not Available
• Not Available - Responsible disclosure to Cisco
• Not Available - CVE CVE-2025-20206 assigned
• Not Available - Cisco releases security patch
• 2025-03-05 - CVE CVE-2025-20206 published to NVD
• 2025-07-22 - Last updated in NVD database

Technical Details for CVE-2025-20206

Vulnerability Analysis

This vulnerability is due to insufficient validation of resources that are loaded by the application at runtime. An attacker could exploit this vulnerability by sending a crafted IPC message to a specific Cisco Secure Client process.

Root Cause

Insufficient validation of dynamically loaded resources within the IPC channel.

Attack Vector

Local exploitation through authenticated IPC message manipulation.

// Example exploitation code (sanitized)
#include <windows.h>

BOOL Exploit() {
    // Load a malicious DLL into the target process
    LoadLibrary("malicious.dll");
    return TRUE;
}

Detection Methods for CVE-2025-20206

Indicators of Compromise

• Unusual DLLs loaded in Cisco Secure Client processes
• Unexpected IPC messages sent to the Cisco Secure Client
• SYSTEM privilege escalation log entries

Detection Strategies

Utilize network monitoring tools to detect abnormal IPC communication and DLL loading patterns in Cisco Secure Client processes.

Monitoring Recommendations

Implement logging of DLL load events and IPC message traffic on all endpoints running Cisco Secure Client. Employ anomaly detection to identify irregular behavior.

How to Mitigate CVE-2025-20206

Immediate Actions Required

• Apply the latest Cisco security patches
• Monitor for unexpected DLL loads
• Limit local administrative access

Patch Information

Cisco has released patches to address this vulnerability. It is critical to apply these updates promptly. Visit the Vendor Advisory for details.

Workarounds

As an immediate workaround, ensure least privilege access and restrict IPC message handling to trusted processes.

# Configuration example
Set-ExecutionPolicy -ExecutionPolicy Bypass
Restrict-LocalAdminAccess.ps1