AWS API MCP Server advisory reports policy checks silently skipped when policy data fails to load

An advisory published July 23 for the AWS API MCP Server (GHSA-29w2-fq35-v728, CVE-2026-16584) reports that when the server's policy enforcement data fails to load during startup, the per-request policy check is silently skipped for the lifetime of the process. Configured deny and gate rules simply do not apply from that point on. The weakness is classified CWE-455, Non-exit on Failed Initialization: the security control disables itself quietly instead of failing the process.

The advisory notes that underlying IAM permissions still apply, so the bypass removes the server's own policy layer rather than all authorization. The record rates it High at CVSS 7.3 on the v4 scale, with local access and user interaction in the vector.

The affected package is awslabs.aws-api-mcp-server on PyPI from 0.2.13 up to but not including 1.3.47, with 1.3.47 as the patched version. The GHSA record is the primary public source; the quiet failure mode is the reason the score lands as high as it does despite the local-access requirement.