CVE-2025-64127: OS Command Injection RCE Vulnerability

CVE-2025-64127 Overview

An OS command injection vulnerability exists in Zenitel devices due to insufficient sanitization of user-supplied input. The application accepts parameters that are later incorporated into OS commands without adequate validation. This could allow an unauthenticated attacker to execute arbitrary commands remotely, potentially leading to complete system compromise.

Critical Impact

This vulnerability allows unauthenticated remote attackers to execute arbitrary OS commands on affected Zenitel devices, potentially enabling full device takeover, lateral movement within networks, and persistence establishment in industrial control system (ICS) environments.

Affected Products

• Zenitel Station and Device Firmware (VS-IS)
• Zenitel ICS/OT communication devices
• Zenitel embedded firmware installations

Discovery Timeline

• 2025-11-26 - CVE-2025-64127 published to NVD
• 2025-12-01 - Last updated in NVD database

Technical Details for CVE-2025-64127

Vulnerability Analysis

This vulnerability is classified as CWE-78 (Improper Neutralization of Special Elements used in an OS Command), commonly known as OS Command Injection. The root issue stems from the application's failure to properly sanitize user-controlled input before incorporating it into operating system commands.

In command injection attacks, the vulnerable application constructs system commands using external input without proper validation or escaping. Attackers can inject shell metacharacters (such as ;, |, &&, or backticks) to break out of the intended command context and execute arbitrary commands with the privileges of the vulnerable application.

The network-accessible nature of this vulnerability combined with no authentication requirement makes it particularly dangerous in ICS/OT environments where Zenitel devices are commonly deployed for critical communication infrastructure.

Root Cause

The vulnerability originates from insufficient input validation and sanitization mechanisms within the device firmware. When user-supplied parameters are processed, they are passed directly to OS command execution functions without adequate filtering of shell metacharacters or command separators. This architectural flaw allows attackers to append or inject their own commands into the execution flow.

Attack Vector

This vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker can send specially crafted requests to the vulnerable device containing malicious command payloads embedded within expected parameters.

The attack mechanism involves:

1. Identifying a parameter that is incorporated into OS command execution
2. Crafting a payload that includes command separator characters followed by attacker-controlled commands
3. Submitting the malicious request to the target device over the network
4. The injected commands execute with the privileges of the application process

For detailed technical information, see the CISA ICS Advisory ICSA-25-329-03 and the GitHub CSAF Document.

Detection Methods for CVE-2025-64127

Indicators of Compromise

• Unusual outbound network connections from Zenitel devices to external IP addresses
• Unexpected process execution or spawned shells on affected devices
• Log entries showing malformed or suspicious parameter values containing shell metacharacters
• Presence of unauthorized files, scripts, or modified configurations on device filesystems

Detection Strategies

• Monitor network traffic to and from Zenitel devices for anomalous patterns or command-and-control communications
• Implement application-layer inspection to detect shell metacharacters (;, |, &&, $(), backticks) in request parameters
• Deploy network segmentation monitoring to identify unauthorized lateral movement attempts from ICS zones
• Review device logs for evidence of command injection attempts or unexpected command execution

Monitoring Recommendations

• Establish baseline behavior profiles for Zenitel devices and alert on deviations
• Implement real-time alerting for any unauthorized access attempts to management interfaces
• Monitor for firmware integrity changes using file integrity monitoring where possible
• Enable and centralize logging from all Zenitel devices to a SIEM for correlation analysis

How to Mitigate CVE-2025-64127

Immediate Actions Required

• Apply the latest firmware update from Zenitel immediately to remediate the vulnerability
• Isolate affected Zenitel devices behind firewalls and restrict network access to trusted management hosts only
• Disable any unnecessary services or interfaces on affected devices to reduce attack surface
• Implement network segmentation to prevent direct access to ICS/OT devices from untrusted networks

Patch Information

Zenitel has released updated firmware to address this vulnerability. Organizations should download and apply the latest Station and Device Firmware Package (VS-IS) from the Zenitel Firmware Package Download page. Organizations should follow their standard change management procedures while prioritizing deployment given the critical severity rating.

For additional guidance, refer to the official CISA ICS Advisory ICSA-25-329-03.

Workarounds

• Place affected devices behind a properly configured firewall that filters malicious input patterns
• Implement network-level access controls to restrict connectivity to only authorized management systems
• Use a VPN for remote access to device management interfaces rather than exposing them directly
• Disable remote management interfaces if not operationally required until patches can be applied

# Example network segmentation firewall rules
# Restrict access to Zenitel device management ports
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
iptables -A INPUT -p tcp --dport 80 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP