Vulnerability in Amazon awslabs-aws-api-mcp-server (CVE-2026-4270)
Summary
Vulnerability in Amazon awslabs-aws-api-mcp-server (CVE-2026-4270). Confidential information can be exposed externally. Mitigation: upgrade to 1.3.9 or later.
Original description
The description as published by the source.
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.
Source: AWS Security Bulletins NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-4270 has been found in Amazon awslabs-aws-api-mcp-server.
Confidential information can be exposed externally. CVSS score: 5.5/10.
What to do: upgrade Amazon awslabs-aws-api-mcp-server to 1.3.9 or later.
If unsure, ask your IT team or search "Amazon awslabs-aws-api-mcp-server CVE-2026-4270" on the vendor's site.
CVE-2026-4270 (Amazon awslabs-aws-api-mcp-server) — CWE-424 / CVSS v3 5.5
Attack vector: local / unauthenticated
Patched: 1.3.9 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-424) exists in Amazon awslabs-aws-api-mcp-server.
Check the vendor advisory for the affected versions of Amazon awslabs-aws-api-mcp-server.
Severity: Medium (CVSS 5.5/10). Confidential information can be exposed externally.
Update to 1.3.9.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'awslabs-aws-api-mcp-server' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'awslabs-aws-api-mcp-server' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
awslabs-aws-api-mcp-serverを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Amazon awslabs-aws-api-mcp-server to 1.3.9ステージング環境で 1.3.9 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory aws.amazon.com
- advisory pypi.org
- advisory nvd.nist.gov
- advisory github.com
- AWS aws.amazon.com
- package github.com
- web github.com
- web aws.amazon.com
- web pypi.org
- web github.com