How severe is CVE-2026-4270?

CVE-2026-4270 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-4270 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4270?

CVE-2026-4270 affects Amazon Aws Api Mcp Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-4270?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-4270 have an EU (EUVD) identifier?

Yes. CVE-2026-4270 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12474.

When was CVE-2026-4270 published?

CVE-2026-4270 was published on 2026-03-16 and last updated on 2026-06-17.

CVE-2026-4270

CVE-2026-4270 is a medium-severity vulnerability in Amazon Aws Api Mcp Server with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-424.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v4: 6.8
EPSS exploit prediction: 0% (3rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12474
Weakness: CWE-424
Affected product: Amazon Aws Api Mcp Server
Published: 2026-03-16
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-4270?: CVE-2026-4270 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-4270 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4270?: CVE-2026-4270 affects Amazon Aws Api Mcp Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-4270?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-4270 have an EU (EUVD) identifier?: Yes. CVE-2026-4270 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12474.
When was CVE-2026-4270 published?: CVE-2026-4270 was published on 2026-03-16 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:amazon:aws_api_mcp_server:*:*:*:*:*:python:*:*

Other CWE-424 vulnerabilities

CVE-2025-48827 — Critical (CVSS 10.0): vBulletin 5.0.0 through 5.7.5 and 6.0.0 through 6.0.3 allows unauthenticated users to invoke protected API controllers'…
CVE-2025-48828 — Critical (CVSS 9.0): Certain vBulletin versions might allow attackers to execute arbitrary PHP code by abusing Template Conditionals in the…
CVE-2024-58136 — Critical (CVSS 9.0): Yii 2 before 2.0.52 mishandles the attaching of behavior that is defined by an __class array key, a CVE-2024-4990…
CVE-2023-52952 — High (CVSS 8.5): A vulnerability has been identified in HiMed Cockpit 12 pro (J31032-K2017-H259) (All versions >= V11.5.1 < V11.6.2),…
CVE-2024-3459 — High (CVSS 8.4): KioWare for Windows (versions all through 8.34) allows to escape the environment by downloading PDF files, which then…
CVE-2025-68939 — High (CVSS 8.2): Gitea before 1.23.0 allows attackers to add attachments with forbidden file extensions by editing an attachment name…

Browse all CWE-424 vulnerabilities →