Improper Protection of Alternate Path in AWS API MCP Server
CVE-2026-4270

6.8MEDIUM

Key Information:

Vendor

Aws

Status
Aws Api Mcp Server
Vendor
CVE Published:
16 March 2026

What is CVE-2026-4270?

A security flaw in the AWS API MCP Server, specifically in the no-access and workdir features, allows for the bypass of intended file access restrictions. This can lead to exposure of arbitrary local file contents within the MCP client application context. Users are advised to upgrade to version 1.3.9 to remediate this issue and protect against unauthorized access.

Affected Version(s)

AWS API MCP Server 0.2.14 < 1.3.9

References

https://aws.amazon.com/security/security-bulletins/2026-0...
vendor-advisory
https://pypi.org/project/awslabs.aws-api-mcp-server/1.3.9/
patch

CVSS V4

Score:
6.8
Severity:
MEDIUM
Confidentiality:
High
Integrity:
None
Availability:
None
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.