CVE-2026-16584

AWS API MCP Server Security Policy Bypass via Startup Failure

State: Published
Severity: 7.3 High
Published: Jul 23, 2026
Updated: Jul 23, 2026
Reserved: Jul 22, 2026

Description

Improper handling of an initialization failure in AWS API MCP Server from 0.2.13 through 1.3.46 might allow an actor to bypass the user-configured security policy and execute AWS API operations that the policy was set to deny or gate. When initialization of the security policy enforcement data fails at server startup, the policy check is skipped for the lifetime of the process. IAM permissions on the configured credentials remain in effect and are unaffected.

To remediate this issue, users should upgrade to version 1.3.47.

Scores

CVSS	Score	Vector	Source
4.0	7.3 High	CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N	AMZN
3.1	7.0 High	CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H	AMZN

Weaknesses

CWE-455 Non-exit on failed initialization

Affected Products

Product	Versions
aws-api-mcp-serverAWS	0.2.13 to before 1.3.47Affected

References

https://pypi.org/project/awslabs.aws-api-mcp-server/1.3.47/release-notespatch
https://aws.amazon.com/security/security-bulletins/2026-063-aws/vendor-advisory
https://github.com/awslabs/mcp/security/advisories/GHSA-29w2-fq35-v728release-notes

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