CVE-2026-7159: mkdocs-mcp-plugin Path Traversal Flaw

CVE-2026-7159 Overview

A path traversal vulnerability has been identified in douinc mkdocs-mcp-plugin versions up to 0.4.1. This vulnerability affects the read_document and list_documents functions within the server.py file. By manipulating the docs_dir or file_path arguments, an attacker can traverse directory boundaries and access files outside the intended documentation directory. The vulnerability can be exploited remotely, and exploit details have been publicly disclosed.

Critical Impact
Remote attackers can read arbitrary files on systems running vulnerable versions of mkdocs-mcp-plugin, potentially exposing sensitive configuration files, credentials, or other confidential data stored on the server.

Affected Products

douinc mkdocs-mcp-plugin versions up to 0.4.1
Applications utilizing the MkDocs MCP Plugin for documentation serving
Systems exposing the plugin's server endpoint to network access

Discovery Timeline

2026-04-27 - CVE-2026-7159 published to NVD
2026-04-29 - Last updated in NVD database

Technical Details for CVE-2026-7159

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), commonly known as Path Traversal. The flaw exists in the server.py file where the read_document and list_documents functions fail to properly sanitize user-supplied path parameters.

When processing requests, the application concatenates user-controlled input (docs_dir and file_path parameters) to construct file system paths without adequate validation. This allows attackers to inject directory traversal sequences (such as ../) to escape the intended documentation directory and access arbitrary files on the server's file system.

The vulnerability is exploitable remotely over the network without requiring authentication or user interaction. An attacker with network access to the vulnerable endpoint can craft malicious requests to read sensitive files outside the documentation root.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and path canonicalization within the read_document and list_documents functions in server.py. The code fails to implement proper checks to ensure that user-supplied path components remain within the designated documentation directory.

Specifically, the application does not:

Sanitize or reject path traversal sequences like ../ or ..\\
Validate that the resolved path remains within the expected base directory
Use secure path handling methods to prevent directory escape

Attack Vector

The attack can be carried out remotely over the network. An attacker can exploit this vulnerability by sending crafted HTTP requests to the vulnerable plugin endpoint. By including path traversal sequences in the docs_dir or file_path parameters, the attacker can navigate the file system hierarchy and read files outside the intended documentation directory.

The exploitation mechanism involves:

Identifying a server running a vulnerable version of mkdocs-mcp-plugin
Crafting malicious requests with path traversal sequences in the vulnerable parameters
Accessing sensitive files such as /etc/passwd, configuration files, or application secrets

For technical details on this vulnerability, refer to the GitHub Issue Discussion and the VulDB entry.

Detection Methods for CVE-2026-7159

Indicators of Compromise

HTTP requests containing path traversal sequences (../, ..\\, %2e%2e%2f) in URL parameters or request bodies directed at mkdocs-mcp-plugin endpoints
Unusual file access patterns in server logs showing attempts to read files outside the documentation directory
Error messages or responses indicating attempts to access system files such as /etc/passwd or configuration files
Network traffic patterns showing reconnaissance activity targeting documentation endpoints

Detection Strategies

Implement web application firewall (WAF) rules to detect and block requests containing path traversal patterns
Monitor web server access logs for suspicious request patterns involving ../ sequences or encoded variants
Deploy intrusion detection system (IDS) signatures to identify path traversal exploitation attempts
Use application security monitoring tools to alert on file access outside expected directories

Monitoring Recommendations

Enable detailed logging for the mkdocs-mcp-plugin and review logs regularly for anomalous requests
Configure alerts for file system access patterns that indicate attempted directory traversal
Implement network monitoring to detect reconnaissance and exploitation attempts targeting documentation servers
Regularly audit systems running mkdocs-mcp-plugin for signs of unauthorized file access

How to Mitigate CVE-2026-7159

Immediate Actions Required

Upgrade mkdocs-mcp-plugin to a patched version once released by the vendor
Restrict network access to mkdocs-mcp-plugin endpoints to trusted networks or users only
Implement web application firewall rules to block requests containing path traversal sequences
Review server logs for evidence of prior exploitation attempts

Patch Information

The vendor has confirmed that a fix will be published within a few days. Organizations should monitor the mkdocs-mcp-plugin GitHub repository for security updates and apply patches immediately upon release.

Until a patch is available, implementing network-level access controls and WAF rules provides defense-in-depth protection against exploitation attempts.

Workarounds

Deploy network access controls to limit who can reach the mkdocs-mcp-plugin endpoints
Configure a reverse proxy or WAF to filter requests containing path traversal patterns before they reach the application
Consider temporarily disabling the affected plugin functionality until a patch is available
Implement strict input validation at the network perimeter to sanitize potentially malicious path parameters

bash

# Example WAF rule to block path traversal attempts (NGINX configuration)
location / {
    if ($request_uri ~* "\.\.\/") {
        return 403;
    }
    if ($request_uri ~* "%2e%2e%2f") {
        return 403;
    }
}