CVE-2025-64126: OS Command Injection RCE Vulnerability

CVE-2025-64126 Overview

CVE-2025-64126 is an OS command injection vulnerability that exists due to improper input validation in Zenitel devices. The application accepts a parameter directly from user input without verifying it is a valid IP address or filtering potentially malicious characters. This could allow an unauthenticated attacker to inject arbitrary commands, leading to complete system compromise.

Critical Impact

This vulnerability allows unauthenticated remote attackers to execute arbitrary OS commands on affected Zenitel devices, potentially leading to full system compromise, data exfiltration, and lateral movement within connected networks.

Affected Products

• Zenitel Station and Device Firmware (VS-IS)

Discovery Timeline

• 2025-11-26 - CVE-2025-64126 published to NVD
• 2025-12-01 - Last updated in NVD database

Technical Details for CVE-2025-64126

Vulnerability Analysis

This vulnerability falls under CWE-78 (Improper Neutralization of Special Elements used in an OS Command), commonly known as OS Command Injection. The flaw originates from the application's failure to properly validate and sanitize user-supplied input before incorporating it into system commands.

When the application receives input intended to be an IP address, it passes this data directly to an operating system command without adequate validation. Attackers can exploit this by including shell metacharacters and command separators (such as ;, |, &&, or backticks) within their input, causing the system to execute additional arbitrary commands with the privileges of the running application.

The network-accessible nature of this vulnerability combined with no authentication requirements makes it particularly dangerous for exposed Zenitel devices, especially in industrial control system (ICS) environments where these devices are commonly deployed.

Root Cause

The root cause is improper input validation in the application's handling of user-supplied IP address parameters. The code fails to implement proper sanitization mechanisms to filter potentially malicious characters before the input is used in operating system command execution. This allows shell metacharacters to be interpreted by the underlying operating system, enabling command injection attacks.

Attack Vector

The vulnerability is exploitable over the network without requiring authentication. An attacker can craft malicious HTTP requests containing command injection payloads within parameters expected to contain IP addresses. The application passes these parameters directly to system shell commands, allowing the attacker's injected commands to execute on the target system.

For example, instead of providing a legitimate IP address like 192.168.1.1, an attacker could supply input such as 192.168.1.1; malicious_command which would cause both the legitimate operation and the attacker's command to execute.

Technical details regarding the specific exploitation mechanism can be found in the CISA ICS Advisory ICSA-25-329-03.

Detection Methods for CVE-2025-64126

Indicators of Compromise

• Unexpected outbound network connections from Zenitel devices to unknown external IP addresses
• Unusual process spawning on Zenitel devices, particularly shell processes or system utilities
• Web server access logs containing suspicious characters (;, |, &&, `, $()) in IP address parameters
• Unexpected file system modifications or new files appearing on the device

Detection Strategies

• Monitor network traffic for HTTP requests to Zenitel devices containing command injection patterns in URL parameters or POST data
• Implement intrusion detection signatures for common command injection metacharacters targeting Zenitel device endpoints
• Deploy behavioral analysis to detect anomalous process execution patterns on affected devices
• Review web application firewall logs for blocked requests containing shell metacharacters

Monitoring Recommendations

• Enable comprehensive logging on all Zenitel devices and forward logs to a centralized SIEM solution
• Implement network segmentation monitoring to detect lateral movement attempts originating from Zenitel devices
• Configure alerts for any command execution attempts involving common reconnaissance or persistence tools
• Monitor for DNS queries from Zenitel devices that may indicate command-and-control communication

How to Mitigate CVE-2025-64126

Immediate Actions Required

• Apply the latest firmware update from Zenitel immediately to patch the vulnerability
• Isolate affected Zenitel devices from untrusted networks using network segmentation
• Implement strict network access controls to limit which systems can communicate with affected devices
• Review access logs for any signs of exploitation attempts prior to patching

Patch Information

Zenitel has released a firmware update to address this vulnerability. The updated firmware package can be downloaded from the Zenitel Firmware Package Download page.

For additional technical guidance, refer to the CISA ICS Advisory ICSA-25-329-03 and the GitHub CSAF JSON File for detailed remediation information.

Workarounds

• Implement strict network segmentation to prevent untrusted network access to Zenitel devices
• Deploy a web application firewall (WAF) in front of affected devices with rules to block command injection patterns
• Restrict network access to affected devices using firewall rules, allowing only authorized IP addresses
• If remote access is required, use a VPN to limit exposure and add an authentication layer

# Example network segmentation using iptables (adjust for your environment)
# Restrict access to Zenitel device to specific trusted management IP
iptables -A INPUT -s 10.0.0.0/24 -d <zenitel_device_ip> -j ACCEPT
iptables -A INPUT -d <zenitel_device_ip> -j DROP