CVE-2026-4270 MEDIUM

CVE-2026-4270: AWS API MCP File Access Restriction Bypass

Vendor Aws
Product AWS API MCP Server
Weakness CWE-424
Published March 16, 2026
Last update March 16, 2026
View on NVD All CVEs

CVSS base score

5.5/10
Attack vector Local
Attack complexity Low
Privileges required None
User interaction Required
Confidentiality High
Integrity None

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 16, 2026 CVE published
March 16, 2026 Record updated