CVE-2026-7443: mcp-dnstwist RCE Vulnerability

CVE-2026-7443 Overview

A command injection vulnerability has been identified in BurtTheCoder mcp-dnstwist versions up to and including 1.0.4. The vulnerability exists within the fuzz_domain function located in the src/index.ts file of the MCP Interface component. An attacker can exploit this weakness by manipulating the Request argument, enabling the execution of arbitrary operating system commands on the target system.

This vulnerability is remotely exploitable and a public exploit has been made available, increasing the risk of active exploitation. The project maintainers were notified through an issue report but have not yet responded.

Critical Impact
Remote attackers can execute arbitrary OS commands on vulnerable systems running mcp-dnstwist versions up to 1.0.4 by manipulating Request arguments to the MCP Interface.

Affected Products

BurtTheCoder mcp-dnstwist versions up to 1.0.4
MCP Interface component (src/index.ts)
Systems utilizing the fuzz_domain function

Discovery Timeline

April 29, 2026 - CVE-2026-7443 published to NVD
April 29, 2026 - Last updated in NVD database

Technical Details for CVE-2026-7443

Vulnerability Analysis

This vulnerability is classified as CWE-77: Command Injection, which occurs when an application constructs a command string using externally-influenced input without properly neutralizing special elements. In the case of mcp-dnstwist, the fuzz_domain function in src/index.ts processes Request arguments that can be crafted to include shell metacharacters or command separators.

When user-supplied input is passed to the fuzz_domain function without adequate sanitization, an attacker can inject additional commands that will be executed by the underlying operating system with the same privileges as the mcp-dnstwist process.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and sanitization within the fuzz_domain function. The MCP Interface accepts Request arguments that are subsequently used in command construction without proper escaping of shell metacharacters. This allows attackers to break out of the intended command context and execute arbitrary system commands.

Common causes for this type of vulnerability include:

Direct concatenation of user input into shell command strings
Missing or inadequate input validation against dangerous characters
Failure to use parameterized command execution methods

Attack Vector

The attack can be launched remotely over the network. An attacker can craft a malicious Request to the MCP Interface containing command injection payloads within the domain fuzzing parameters. Common injection techniques may include shell command separators (;, |, &&, ||) or command substitution syntax (backticks or $()) to execute arbitrary commands.

The vulnerability mechanism involves manipulating the Request argument passed to the fuzz_domain function. When this tainted input is processed by the MCP Interface without proper sanitization, the injected commands are executed by the underlying shell. For detailed technical analysis, refer to the GitHub Issue #22 and the VulDB entry.

Detection Methods for CVE-2026-7443

Indicators of Compromise

Unusual command execution patterns originating from the mcp-dnstwist process
Unexpected child processes spawned by the Node.js runtime running mcp-dnstwist
Network connections from the mcp-dnstwist process to unexpected external hosts
Log entries showing malformed domain names containing shell metacharacters

Detection Strategies

Monitor process execution logs for suspicious command patterns associated with the mcp-dnstwist process
Implement application-level logging to capture all Request arguments passed to the MCP Interface
Deploy network intrusion detection rules to identify command injection payload patterns in MCP traffic
Use endpoint detection and response (EDR) solutions to monitor for anomalous process trees

Monitoring Recommendations

Enable verbose logging for all MCP Interface interactions
Configure alerts for command execution attempts containing shell metacharacters
Monitor file system changes and network activity from the mcp-dnstwist process
Review access logs for repeated requests with unusual domain name patterns

How to Mitigate CVE-2026-7443

Immediate Actions Required

Restrict network access to the MCP Interface to trusted sources only
Implement additional input validation at the network perimeter or application gateway
Consider disabling the mcp-dnstwist service until a patch is available
Monitor systems running mcp-dnstwist for signs of compromise

Patch Information

At the time of publication, no official patch has been released by the project maintainers. The vulnerability was reported through GitHub Issue #13, but the project has not yet responded. Users should monitor the mcp-dnstwist repository for updates and security fixes.

Workarounds

Implement a Web Application Firewall (WAF) or input filter to block requests containing shell metacharacters
Use network segmentation to isolate systems running mcp-dnstwist from critical infrastructure
Deploy application-level input validation to sanitize all Request arguments before processing
Consider replacing mcp-dnstwist with an alternative DNS fuzzing solution until a fix is available

bash

# Example: Restrict network access to MCP Interface using iptables
# Allow only trusted IP range to access the service
iptables -A INPUT -p tcp --dport 3000 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 3000 -j DROP