Improper Protection of Alternate Path exists in the no-access and workdir feature of the AWS API MCP Server versions >= 0.2.14 and < 1.3.9 on all platforms may allow the bypass ...
Date: 2026-03
Affected: amazon/aws_api_mcp_server
Attack vector: other
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2026-4270
CWE: CWE-424
CVSS: 5.5 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N)

Improper Protection of Alternate Path exists in the no-access and workdir feature of the AWS API MCP Server versions >= 0.2.14 and < 1.3.9 on all platforms may allow the bypass of intended file access restriction and expose arbitrary local file contents in the MCP client application context. To remediate this issue, users should upgrade to version 1.3.9.


Mitigations:

Architectural layers (MAESTRO):