Missing token audience validation in the OAuth authentication mode of AWS API MCP Server before version 1.6.0 might allow local users to run AWS operations with the server's configured AWS credentials via an access token issued to another application by the same identity provider.
To remediate this issue, users should upgrade to version 1.6.0 and configure the expected token audience or client ID for the server.
Attack Parameters
Attack Vector
Local
Requires local access
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
References 3
https://aws.amazon.com/security/security-bulletins/2026-152-aws/
ff89ba41-3aa1-4d27-914a-91399e9639e5
https://github.com/awslabs/mcp/security/advisories/GHSA-4prq-p2x5-w9fh
ff89ba41-3aa1-4d27-914a-91399e9639e5
https://pypi.org/project/awslabs.aws-api-mcp-server/1.6.0/
ff89ba41-3aa1-4d27-914a-91399e9639e5