Bulletin ID: 2026-149-AWS
Scope: AWS
Content Type: Important (requires attention)
Publication Date: 10/23/2026 12:00 PM PDT

Description:

AWS MCP Server is a managed server that gives AI agents access to AWS through the Model Context Protocol (MCP), including a run_script tool that runs Python scripts in a sandboxed environment.

We identified CVE-2026-115845, an issue in the Python code validator of the run_script tool in AWS MCP Server. An incomplete list of disallowed inputs might allow an authenticated remote user to execute arbitrary code within their own isolated session environment via a crafted script.

Impacted versions: N/A (managed service, exclusively hosted)

Resolution:

This issue has been addressed service-side. No customer action is required.

Workarounds:

The run_script tool is designed to orchestrate AWS APIs through a Python script. If you use it only to run a Python script that makes AWS API calls, no workaround is required.

References:

• CVE-2026-115845

Acknowledgement:

We would like to thank Manash Saikiafor collaborating on this issue through the coordinated vulnerability disclosure process.

Please email aws-security@amazon.com with any security questions or concerns.