Mastra is a Typescript framework for building AI agents and assistants. Versions 0.13.8 through 0.13.20-alpha.0 are vulnerable to a Directory Traversal attack that results in the disclosure of directory listings. The code contains a security check to prevent path traversal for reading file contents, but this check is effectively bypassed by subsequent logic that attempts to find directory suggestions. An attacker can leverage this flaw to list the contents of arbitrary directories on the user's filesystem, including the user's home directory, exposing sensitive information about the file system's structure. This issue is fixed in version 0.13.20.

Affected: npm: @mastra/mcp-docs-server

The Mastra Docs MCP Server package `@mastra/mcp-docs-server` is a server designed to provide documentation context to AI agentic workflows, such as those used in AI-powered IDEs.

**Resources:**

* Package URL: [https://www.npmjs.com/package/@mastra/mcp-docs-server](https://www.npmjs.com/package/@mastra/mcp-docs-server)

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## Overview

The `@mastra/mcp-docs-server` package in versions **0.13.18 and below** is vulnerable to a Directory Traversal attack that results in the disclosure of directory listings. The code contains a security check to prevent path traversal for reading file contents, but this check is effectively bypassed by subsequent logic that attempts to find directory suggestions. An attacker can leverage this flaw to list the contents of arbitrary directories on the user's filesystem, including the user's home directory, exposing sensitive information about the file system's structure.

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## Vulnerability

The tool's code attempts to prevent path traversal within the `readMdxContent` function. It correctly checks if the resolved path is within the intended base directory. If the check fails, it logs an error and returns `{ found: false }`.

*File: `src/tools/docs.ts`*

```js async function readMdxContent(docPath: string, queryKeywords: string[]): Promise<ReadMdxResult> { const fullPath = path.resolve(path.join(docsBaseDir, docPath)); if (!fullPath.startsWith(path.resolve(docsBaseDir))) { void logger.error(`Path traversal attempt detected`);…