What is CVE-2026-4270?

CVE-2026-4270 is a medium-severity vulnerability in Amazon Aws Api Mcp Server, classified under CWE-424. CVSS score: 5.5/10. Published 2026-03-16.

How severe is CVE-2026-4270?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Vulnerability in Amazon Aws Api Mcp Server

CVE-2026-4270

Improper Protection of Alternate Path exists in the no-access and workdir feature of the AWS API MCP Server versions >= 0.2.14 and < 1.3.9 on all platforms may allow the bypass of intended file access restriction and expose arbitrary local file contents in the MCP client application context. To remediate this issue, users should upgrade to version 1.3.9.

EPSS: 0.001 (3.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

Affected products

Amazon Aws_api_mcp_server
Aws Api Mcp Server — versions 0.2.14

Weakness classification (CWE)

CWE-424

References

ff89ba41-3aa1-4d27-914a-91399e9639e5 (vendor-advisory, Vendor Advisory)
ff89ba41-3aa1-4d27-914a-91399e9639e5 (Third Party Advisory, patch)

Frequently asked questions

What is CVE-2026-4270?: CVE-2026-4270 is a medium-severity vulnerability in Amazon Aws Api Mcp Server, classified under CWE-424. CVSS score: 5.5/10. Published 2026-03-16.
How severe is CVE-2026-4270?: Medium severity. CVSS v3 base score is 5.5 out of 10.