CVE-2026-4270: CWE-424: Improper Protection of Alternate Path in AWS AWS API MCP Server
CVE-2026-4270 is a medium severity vulnerability in AWS API MCP Server versions from 0.2.14 up to but not including 1.3.9. It involves improper protection of an alternate path in the no-access and workdir feature, which may allow bypassing intended file access restrictions and exposing arbitrary local file contents within the MCP client application context. The vulnerability impacts confidentiality but does not affect availability or integrity. No known exploits have been reported in the wild. Users are advised to upgrade to version 1.3 or later to address this issue.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-4270) affects AWS API MCP Server versions 0.2.14 through before 1.3.9. It is caused by improper protection of an alternate path related to the no-access and workdir feature, allowing attackers to bypass file access restrictions and read arbitrary local files within the MCP client application context. The issue impacts confidentiality but does not compromise data integrity or system availability. The CVSS 3.1 base score is 5.5, reflecting medium severity with local attack vector, low complexity, no privileges required, and user interaction needed.
Potential Impact
An attacker with local access and the ability to interact with the MCP client application could potentially bypass intended file access restrictions and read arbitrary local files, leading to confidentiality breaches. There is no impact on system availability or data integrity. No known exploits have been observed in the wild.
Mitigation Recommendations
Users should upgrade AWS API MCP Server to version 1.3 or later, where this vulnerability is fixed. Since this is not a cloud service, remediation depends on user action to apply the update. Patch status is confirmed by the vendor advisory recommending upgrading to version 1.3.
CVE-2026-4270: CWE-424: Improper Protection of Alternate Path in AWS AWS API MCP Server
Description
CVE-2026-4270 is a medium severity vulnerability in AWS API MCP Server versions from 0.2.14 up to but not including 1.3.9. It involves improper protection of an alternate path in the no-access and workdir feature, which may allow bypassing intended file access restrictions and exposing arbitrary local file contents within the MCP client application context. The vulnerability impacts confidentiality but does not affect availability or integrity. No known exploits have been reported in the wild. Users are advised to upgrade to version 1.3 or later to address this issue.
CVSS v3.1
Score 5.5medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-4270) affects AWS API MCP Server versions 0.2.14 through before 1.3.9. It is caused by improper protection of an alternate path related to the no-access and workdir feature, allowing attackers to bypass file access restrictions and read arbitrary local files within the MCP client application context. The issue impacts confidentiality but does not compromise data integrity or system availability. The CVSS 3.1 base score is 5.5, reflecting medium severity with local attack vector, low complexity, no privileges required, and user interaction needed.
Potential Impact
An attacker with local access and the ability to interact with the MCP client application could potentially bypass intended file access restrictions and read arbitrary local files, leading to confidentiality breaches. There is no impact on system availability or data integrity. No known exploits have been observed in the wild.
Mitigation Recommendations
Users should upgrade AWS API MCP Server to version 1.3 or later, where this vulnerability is fixed. Since this is not a cloud service, remediation depends on user action to apply the update. Patch status is confirmed by the vendor advisory recommending upgrading to version 1.3.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- AMZN
- Date Reserved
- 2026-03-16T14:28:58.998Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 69b8316f9d4df4518370fea8
Added to database: 3/16/2026, 4:35:59 PM
Last enriched: 6/5/2026, 7:29:50 PM
Last updated: 6/15/2026, 3:22:19 AM
Views: 172
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