CVE-2026-16584
Bulletin ID: 2026-063-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 07/23/2026 08:30 AM PDT Description: The AWS API MCP Server (awslabs.aws-api-mcp-server) is an open-source MCP server that lets AI assistants execute AWS CLI commands against a user's AWS account. It includes an optional, user-configured security policy that can deny or gate specific AWS operations. We identified CVE-2026-16584. On startup, the server loads the data used to enforce this security policy. If that initialization fails, the server continues running with the per-request policy check skipped for the lifetime of the process. When a security policy is configured without the fail-closed modes enabled, an actor could then cause AWS API operations that the policy was configured to deny or gate to execute without enforcement. IAM permissions on the configured credentials remain in effect and are unaffected. Impacted versions: >= 0.2.13 AND < 1.3.47 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.
CSIRTS triage
- What
- A security policy bypass vulnerability exists due to a failure in server startup initialization.
- Who is affected
- Users of the AWS API MCP Server with configured security policies.
- Urgency
- Remediation is important as it could allow unauthorized AWS operations, but exploitation is not confirmed.
- Action
- Users should review and update their security policies and monitor server startup processes.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all EPSS-scored CVEs.
Advisory coverage (3)
- highGHSA-29w2-fq35-v728: AWS API MCP Server Security Policy Bypass via Startup Initialization Failureghsa · 2026-07-24
- highCVE-2026-16584: Improper handling of an initialization failure in AWS API MCP Server from 0.2.13 through 1.3.4…nvd · 2026-07-23
- unknownCVE-2026-16584 - AWS API MCP Server Security Policy Bypass via Startup Failureaws · 2026-07-23
External references
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