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.

Attack Vector Local

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction Passive

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Local

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact None

Availability Impact None

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
AWS AWS API MCP Server unaffected
Version Status Constraints
0.2.14 affected < 1.3.9

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Project Subscriptions

No data.

Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://aws.amazon.com/security/security-bulletins/2026-007-AWS/ cve-icon cve-icon
https://pypi.org/project/awslabs.aws-api-mcp-server/1.3.9/ cve-icon cve-icon
History

Mon, 16 Mar 2026 16:30:00 +0000

Type Values Removed Values Added
Description 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.
Title AWS API MCP File Access Restriction Bypass
Weaknesses CWE-424
References
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N'}

cvssV4_0

{'score': 6.8, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: AMZN

Published:

Updated: 2026-03-16T18:17:17.927Z

Reserved: 2026-03-16T14:28:58.998Z

Link: CVE-2026-4270

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-16T17:16:32.270

Modified: 2026-03-16T17:16:32.270

Link: CVE-2026-4270

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses