CVE-2026-51997 in mcp-remote
Summary
by MITRE • 09/24/2026
An issue in geelen mcp-remote 0.1.16 through 0.1.38 allows a remote attacker to execute arbitrary code via the open() functions
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Analysis
by VulDB Data Team • 09/24/2026
The vulnerability identified within geelen mcp-remote versions 0.1.16 through 0.1.38 represents a critical security flaw rooted in improper input validation and handling of file operations. This software, which facilitates remote model context protocol interactions, contains a weakness in its open() function implementation that permits a remote attacker to execute arbitrary code on the target system. The core technical issue stems from the application's failure to adequately sanitize or validate user-supplied data before passing it to underlying operating system calls responsible for opening files or resources. When an untrusted input is processed without rigorous checks, it can lead to path traversal scenarios or injection attacks where malicious payloads are interpreted as executable commands rather than benign file paths. This lack of strict boundary enforcement allows the application logic to be subverted, effectively granting the attacker control over the execution flow within the context of the running process.
From a technical perspective, this flaw aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command and potentially CWE-22 Path Traversal if file system access is manipulated to read or write sensitive data outside intended directories. The open() function serves as a critical interface between the application layer and the operating system kernel. If this interface accepts unsanitized strings that contain shell metacharacters, directory traversal sequences such as dot-dot-slash, or other exploit-specific payloads, it creates an avenue for command injection. In many modern applications utilizing remote procedure calls or network-based protocols like MCP, inputs are often transmitted over the wire without sufficient integrity verification at the application level before being processed locally. The vulnerability in geelen mcp-remote suggests that these inputs were directly concatenated into system commands or passed to unsafe library functions that do not perform their own security checks against injection vectors.
The operational impact of this vulnerability is severe, as successful exploitation results in remote code execution with the privileges of the user account under which the application is running. This level of access allows an attacker to compromise the confidentiality, integrity, and availability of the host system. An adversary could install backdoors, exfiltrate sensitive data stored on the local machine, pivot to other systems within the network, or disrupt service by terminating critical processes. Given that mcp-remote likely handles model contexts which may include proprietary algorithms, training data, or inference results, the breach also poses significant risks to intellectual property and business continuity. The ability to execute arbitrary code means the attacker is not limited to passive information gathering but can actively manipulate the environment, making this a high-severity issue that demands immediate attention.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary solution involves upgrading geelen mcp-remote to version 0.1.39 or later where the developers have presumably addressed these input validation gaps. If an upgrade is not immediately feasible, administrators should implement strict input sanitization at the application boundary, ensuring that all file paths are validated against a whitelist of allowed characters and directories. Utilizing absolute path resolution functions that canonicalize inputs before processing can also prevent traversal attacks. Furthermore, deploying network-level controls such as web application firewalls or intrusion detection systems may help filter out known malicious payloads attempting to exploit this specific vector. From a development lifecycle perspective, integrating static analysis tools and dynamic testing focused on command injection vulnerabilities will help identify similar weaknesses in future releases. Adhering to secure coding standards like OWASP Top 10 guidelines for input validation is essential to prevent recurrence of such critical flaws.
This incident highlights the importance of treating all remote inputs as untrusted until proven otherwise, a principle central to modern cybersecurity frameworks including MITRE ATT&CK technique T1059 Command and Scripting Interpreter which describes how attackers leverage system utilities to execute commands. By understanding that functions like open() are potential entry points for privilege escalation if mishandled, security teams can better prioritize patch management and code review processes. The vulnerability serves as a reminder that even minor utility libraries in complex software stacks can become significant attack vectors when basic security hygiene is neglected during development.