6.8

CVE-2026-4270: amazon aws_api_mcp_server Improper Protection of Alternate Path

CVSS: 6.8v4.0MediumAnalyzed
AliasesGHSA-2cpp-j2fc-qhp7PYSEC-2026-162
Published 16-03-2026Last modified 16-03-2026
Open JSON

Vulnerability summary

CVE-2026-4270 is a medium (CVSS 6.8) Improper Protection of Alternate Path vulnerability in amazon aws_api_mcp_server. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 7.9% of scored vulnerabilities.

Overall risk
27/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.8/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.19%
0%100%
Low · +0.06 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 16-03-2026
    PublishedVulnerability first disclosed.
  2. 16-03-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

5 scores · 3 sources · 2 versions

EPSS trend

Probability

0.19%

Chance of exploitation in the next 30 days

Percentile

8%

Versus all other CVEs

30-day change

+0.06 pp

From 0.13% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.19%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Amazon1 product
Aws1 product
PyPI1 product
  • awslabs-aws-api-mcp-server≥ 0.2.14, < 1.3.9

3 vendors · 3 products

References

9 links