Improper handling of an initialization failure in AWS API MCP Server may allow a malicious actor to bypass a user‑configured security policy and execute API operations that the policy was intended to deny. The vulnerability is a classic initialization‑time failure that skips policy enforcement for the lifetime of the process, enabling any operation permitted by the IAM credentials in use. This weakens the integrity of access control and can expose privileged actions to unauthorized users.

AWS API MCP Server versions 0.2.13 through 1.3.46 are affected. The flaw remains until the server is upgraded to version 1.3.47 or later, which contains the necessary protection against policy initialization failures.

The CVSS score of 7.3 indicates a high potential impact, but the EPSS score of <1% reflects a low probability of exploitation in the wild, and the vulnerability is not listed in the CISA KEV catalog. The most likely attack vector is a local or configuration‑based attack that triggers an initialization failure; when the policy cannot be loaded, enforcement is disabled and the process continues running with the underlying IAM permissions. If an attacker can induce such a failure—by tampering with configuration files, dependencies or environment variables—they can gain unrestricted access to the APIs governed by that server.