CVE-2025-61489: sonirico mcp-shell RCE Vulnerability

CVE-2025-61489 Overview

A command injection vulnerability exists in the shell_exec function of sonirico mcp-shell version 0.3.1. This vulnerability allows attackers to execute arbitrary commands on the underlying system by supplying a crafted command string. The flaw stems from improper input validation (CWE-77) in the shell execution functionality, enabling remote attackers to inject malicious commands that are then executed with the privileges of the application.

Critical Impact

Remote attackers can execute arbitrary system commands without authentication, potentially leading to unauthorized access, data exfiltration, or full system compromise.

Affected Products

• sonirico mcp-shell v0.3.1

Discovery Timeline

• 2026-01-07 - CVE CVE-2025-61489 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-61489

Vulnerability Analysis

This command injection vulnerability is classified under CWE-77 (Improper Neutralization of Special Elements used in a Command). The vulnerability resides in the shell_exec function within the mcp-shell component. When processing user-supplied input, the function fails to properly sanitize or validate command strings before passing them to the underlying shell for execution.

The network-accessible attack vector allows remote exploitation without requiring user interaction or prior authentication. When exploited, attackers can achieve partial compromise of both confidentiality and integrity on the target system.

Root Cause

The root cause of this vulnerability is insufficient input validation and sanitization in the shell_exec function. The function accepts command strings from external sources and passes them directly to shell execution routines without properly escaping or filtering special characters and command separators. This allows attackers to append or inject additional commands using shell metacharacters such as semicolons (;), pipes (|), command substitution ($()), and other shell-specific syntax.

Attack Vector

The vulnerability is exploitable over the network with low attack complexity. An attacker can craft malicious input containing shell metacharacters or command injection payloads that, when processed by the shell_exec function, result in the execution of arbitrary commands on the target system.

Common injection techniques include:

• Command chaining using ;, &&, or || operators
• Command substitution via backticks or $()
• Piping output to additional commands using |

The vulnerability allows exploitation without authentication and requires no user interaction, making it particularly dangerous in exposed deployments. Technical details and proof-of-concept information can be found in the GitHub Issue Discussion.

Detection Methods for CVE-2025-61489

Indicators of Compromise

• Unexpected process spawning from the mcp-shell application
• Unusual command-line arguments containing shell metacharacters (;, |, &&, $(, backticks)
• Network connections originating from the mcp-shell process to unexpected destinations
• Log entries showing malformed or suspicious command strings being processed

Detection Strategies

• Monitor system logs for anomalous command execution patterns originating from the mcp-shell process
• Implement application-level logging to capture all input passed to the shell_exec function
• Deploy network intrusion detection rules to identify payloads containing common command injection patterns
• Use endpoint detection solutions to alert on suspicious child processes spawned by the mcp-shell application

Monitoring Recommendations

• Enable verbose logging for the mcp-shell application to capture all command execution requests
• Implement file integrity monitoring on critical system files and directories
• Monitor for unexpected outbound network connections that may indicate command-and-control activity
• Review process creation events for unusual parent-child process relationships involving mcp-shell

How to Mitigate CVE-2025-61489

Immediate Actions Required

• Audit all deployments of mcp-shell v0.3.1 and identify internet-exposed instances
• Restrict network access to mcp-shell instances using firewall rules or network segmentation
• Implement input validation at the application boundary to filter shell metacharacters
• Consider temporarily disabling the shell_exec functionality until a patch is available

Patch Information

At the time of publication, no official patch has been released for this vulnerability. Organizations should monitor the mcp-shell GitHub repository for updates and security releases. The GitHub Issue Discussion provides additional context and may contain interim mitigation guidance from the maintainers.

Workarounds

• Implement a web application firewall (WAF) or input filter to block requests containing shell metacharacters
• Deploy the application in a sandboxed environment with restricted system permissions
• Use allow-listing for permitted commands rather than relying on blocklisting malicious patterns
• Consider running the application with minimal privileges using dedicated service accounts

# Example: Restrict network access to mcp-shell using iptables
# Only allow connections from trusted internal network
iptables -A INPUT -p tcp --dport <mcp-shell-port> -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport <mcp-shell-port> -j DROP