CVE-2025-11546: CLUSTERPRO X for Linux RCE Vulnerability

CVE-2025-11546 Overview

CVE-2025-11546 is a critical command injection vulnerability (CWE-78) affecting NEC CLUSTERPRO X and EXPRESSCLUSTER X high-availability clustering software for Linux. The vulnerability allows unauthenticated remote attackers to execute arbitrary operating system commands by sending specially crafted network packets to the affected products. This flaw poses a severe risk to enterprise environments relying on these clustering solutions for business continuity and failover capabilities.

Critical Impact

Unauthenticated remote attackers can execute arbitrary OS commands on affected CLUSTERPRO X and EXPRESSCLUSTER X systems without any authentication, potentially leading to complete system compromise.

Affected Products

• CLUSTERPRO X for Linux versions 4.0, 4.1, 4.2, 5.0, 5.1, and 5.2
• EXPRESSCLUSTER X for Linux versions 4.0, 4.1, 4.2, 5.0, 5.1, and 5.2
• CLUSTERPRO X SingleServerSafe for Linux versions 4.0, 4.1, 4.2, 5.0, 5.1, and 5.2
• EXPRESSCLUSTER X SingleServerSafe for Linux versions 4.0, 4.1, 4.2, 5.0, 5.1, and 5.2

Discovery Timeline

• 2025-11-07 - CVE-2025-11546 published to NVD
• 2025-11-12 - Last updated in NVD database

Technical Details for CVE-2025-11546

Vulnerability Analysis

This vulnerability is classified as OS Command Injection (CWE-78), which occurs when an application passes unsafe user-supplied data to a system shell. In the case of CVE-2025-11546, the CLUSTERPRO X and EXPRESSCLUSTER X clustering software fails to properly sanitize or validate input from network packets before processing them in a manner that allows OS command execution.

The network-accessible nature of this vulnerability combined with the lack of authentication requirements makes it particularly dangerous. An attacker with network access to the affected clustering software can send malicious packets that bypass input validation and inject arbitrary commands into the underlying operating system context.

Root Cause

The root cause of this vulnerability lies in improper input validation when processing network packets. The affected products do not adequately sanitize user-controlled input before passing it to system shell functions, allowing metacharacters and command sequences to be interpreted as executable commands. This is a classic command injection pattern where the application constructs OS commands using untrusted external input without proper neutralization of special elements.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying a target system running a vulnerable version of CLUSTERPRO X or EXPRESSCLUSTER X
2. Crafting specially formatted network packets containing malicious command payloads
3. Sending these packets to the clustering service
4. The service processes the packets without proper input validation
5. Injected commands are executed with the privileges of the clustering service process

The vulnerability mechanism involves improper handling of special characters in network packet data that is subsequently used in OS command execution contexts. When the clustering software processes these packets, it fails to sanitize command metacharacters such as semicolons, pipes, or backticks, allowing attackers to append or inject additional commands. For detailed technical information, refer to the NEC Security Advisory NV25-006.

Detection Methods for CVE-2025-11546

Indicators of Compromise

• Unusual network traffic patterns targeting CLUSTERPRO X or EXPRESSCLUSTER X service ports
• Unexpected process spawning from clustering service parent processes
• Anomalous system command executions with clustering service ownership
• Suspicious entries in system logs indicating command execution attempts

Detection Strategies

• Deploy network intrusion detection systems (NIDS) with signatures for command injection patterns in CLUSTERPRO/EXPRESSCLUSTER traffic
• Monitor process creation events for child processes spawned by clustering services executing unexpected commands
• Implement application-level logging to capture and analyze all network packet processing activities
• Configure endpoint detection and response (EDR) solutions to alert on suspicious command-line patterns originating from clustering processes

Monitoring Recommendations

• Enable verbose logging on CLUSTERPRO X and EXPRESSCLUSTER X installations to capture packet processing details
• Establish baseline network traffic patterns for clustering services and alert on deviations
• Implement file integrity monitoring on critical system files and directories
• Monitor authentication logs for any anomalies even though the vulnerability bypasses authentication

How to Mitigate CVE-2025-11546

Immediate Actions Required

• Review the NEC Security Advisory NV25-006 for official guidance and patches
• Restrict network access to CLUSTERPRO X and EXPRESSCLUSTER X services using firewall rules to trusted management networks only
• Implement network segmentation to isolate clustering infrastructure from untrusted networks
• Monitor affected systems for indicators of compromise until patches can be applied

Patch Information

NEC has published security advisory NV25-006 addressing this vulnerability. Administrators should consult the official NEC security advisory for specific patch information and update instructions for their affected product versions. Apply security updates as soon as they become available for your specific version of CLUSTERPRO X, EXPRESSCLUSTER X, or their SingleServerSafe variants.

Workarounds

• Implement strict network access controls limiting connectivity to clustering services from trusted management hosts only
• Deploy web application firewalls (WAF) or network-based intrusion prevention systems (IPS) with rules to detect and block command injection attempts
• If the clustering service ports are not required to be externally accessible, bind services to localhost or internal interfaces only
• Consider temporarily disabling affected services in non-production environments until patches are applied

# Example: Restrict access to clustering services using iptables
# Allow only trusted management network to access clustering ports
iptables -A INPUT -p tcp -s 10.0.0.0/24 --dport 29001:29003 -j ACCEPT
iptables -A INPUT -p tcp --dport 29001:29003 -j DROP