CVE-2025-20124: Cisco Identity Services Engine RCE Flaw

CVE-2025-20124 Overview

A vulnerability in an API of Cisco ISE could allow an authenticated, remote attacker to execute arbitrary commands as the root user on an affected device. This vulnerability is due to insecure deserialization of user-supplied Java byte streams by the affected software. An attacker could exploit this vulnerability by sending a crafted serialized Java object to an affected API. A successful exploit could allow the attacker to execute arbitrary commands on the device and elevate privileges.

Note: To successfully exploit this vulnerability, the attacker must have valid read-only administrative credentials. In a single-node deployment, new devices will not be able to authenticate during the reload time.

Critical Impact
Unauthorized command execution as root may lead to complete system compromise.

Affected Products

Cisco Identity Services Engine 3.1.0
Cisco Identity Services Engine 3.2.0
Cisco Identity Services Engine 3.3.0

Discovery Timeline

Not Available - Vulnerability discovered by Not Available
Not Available - Responsible disclosure to Cisco
Not Available - CVE CVE-2025-20124 assigned
Not Available - Cisco releases security patch
2025-02-05T17:15:22.457 - CVE CVE-2025-20124 published to NVD
2025-03-28T13:22:42.077 - Last updated in NVD database

Technical Details for CVE-2025-20124

Vulnerability Analysis

This vulnerability arises from the insecure deserialization of Java objects in an API endpoint, allowing attackers with authenticated access to execute arbitrary code on the underlying system.

Root Cause

The affected software improperly deserializes user-supplied Java byte streams, leading to potential command execution vulnerabilities.

Attack Vector

The vulnerability can be exploited over the network by sending malicious serialized Java objects to an exposed API endpoint.

java

// Example exploitation code (sanitized)
ObjectInputStream objectInputStream = new ObjectInputStream(maliciousInputStream);
Object maliciousObject = objectInputStream.readObject();
// Manipulate the deserialized object

Detection Methods for CVE-2025-20124

Indicators of Compromise

Unusual network traffic to API endpoints
Unauthorized services running on Cisco ISE
Unexpected command execution logs on the affected system

Detection Strategies

Implement monitoring for serialized data passed to API endpoints, and alert on anomalies. Use behavior-based detection to identify unauthorized command execution.

Monitoring Recommendations

Regularly review application logs for unauthorized access attempts, and monitor for suspicious serialized object payloads in network traffic.

How to Mitigate CVE-2025-20124

Immediate Actions Required

Disable vulnerable API endpoints if possible
Apply Cisco-provided patches immediately
Monitor for signs of compromise in your environment

Patch Information

Administrators are advised to refer to the Cisco Security Advisory for detailed patch and upgrade instructions.

Workarounds

Limit access to the vulnerable APIs by implementing strict network access controls and ensuring only trusted administrative users can access the API.

bash

# Example firewall configuration to restrict API access
iptables -A INPUT -p tcp --dport <api_port> -s <trusted_ip> -j ACCEPT
iptables -A INPUT -p tcp --dport <api_port> -j DROP