CVE-2026-18953 - Improper limitation of a pathname in AWS Transform MCP Server

CVE-2026-18953 - Improper limitation of a pathname in AWS Transform MCP Server

Bulletin ID: 2026-075-AWS
Scope: AWS
Content Type: Important (requires attention)
Publication Date: 08/05/2026 12:30 PM PDT

The AWS Transform MCP Server (awslabs.aws-transform-mcp-server) is an open-source Model Context Protocol (MCP) server that runs locally on a developer's machine and lets AI-powered assistants interact with AWS Transform to run code-transformation jobs and retrieve their artifacts. We identified CVE-2026-18953. Improper limitation of a pathname to a restricted directory in the get_resource tool in awslabs.aws-transform-mcp-server before 0.1.5 might allow a context-dependent actor to write arbitrary files outside the intended working directory via the savePath parameter, which could lead to local code execution.

This issue has been addressed in awslabs.aws-transform-mcp-server version 0.1.5. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.

There is no server-side or configuration-only workaround; the affected code path is present in the default configuration. Customers must upgrade to version 0.1.5 or later.

We would like to thank Drew Raines for collaborating on this issue through the coordinated issue disclosure process.