CVE-2026-4270 - AWS API MCP File Access Restriction Bypass

Summary

CVE-2026-4270 is an Improper Protection of Alternate Path flaw in the no-access and workdir file access features of the AWS API MCP Server, affecting awslabs.aws-api-mcp-server versions >= 0.2.14 and < 1.3.9 on all platforms. The flaw may allow an attacker to bypass the intended file access restriction and expose arbitrary local file contents in the MCP client application context.

Mitigation

The source does not state a fix yet. Check the original advisory for updates.

Topics

• Model Context Protocol

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