Vulnerability-Lookup

PYSEC-2026-162

Vulnerability from pysec - Published: 2026-03-16 17:16 - Updated: 2026-05-22 17:23

Details

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.

Severity

6.8 (Medium)


                  
                    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

Impacted products

Name	purl
awslabs-aws-api-mcp-server	pkg:pypi/awslabs-aws-api-mcp-server

Aliases

CVE-2026-4270

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {},
      "package": {
        "ecosystem": "PyPI",
        "name": "awslabs-aws-api-mcp-server",
        "purl": "pkg:pypi/awslabs-aws-api-mcp-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.2.14"
            },
            {
              "fixed": "1.3.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.2.14",
        "0.3.0",
        "0.3.1",
        "0.3.2",
        "0.3.3",
        "0.3.4",
        "1.0.0",
        "1.0.1",
        "1.0.2",
        "1.1.0",
        "1.1.1",
        "1.1.2",
        "1.1.3",
        "1.1.4",
        "1.1.5",
        "1.1.6",
        "1.1.7",
        "1.1.8",
        "1.2.0",
        "1.2.1",
        "1.2.2",
        "1.2.3",
        "1.3.0",
        "1.3.1",
        "1.3.2",
        "1.3.3",
        "1.3.4",
        "1.3.5",
        "1.3.6",
        "1.3.7",
        "1.3.8"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-4270"
  ],
  "details": "Improper Protection of Alternate Path exists in the no-access and workdir feature of the AWS API MCP Server versions \u003e= 0.2.14 and \u003c 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.\n\nTo remediate this issue, users should upgrade to version 1.3.9.",
  "id": "PYSEC-2026-162",
  "modified": "2026-05-22T17:23:49.899310Z",
  "published": "2026-03-16T17:16:32.270Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://aws.amazon.com/security/security-bulletins/2026-007-AWS/"
    },
    {
      "type": "ADVISORY",
      "url": "https://pypi.org/project/awslabs.aws-api-mcp-server/1.3.9/"
    }
  ],
  "severity": [
    {
      "score": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-4270 (GCVE-0-2026-4270)

Vulnerability from cvelistv5 – Published: 2026-03-16 16:07 – Updated: 2026-03-16 18:17

Title

AWS API MCP File Access Restriction Bypass

Summary

Severity

5.5 (Medium)


                        
                          CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

6.8 (Medium)


                        
                          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

CWE

CWE-424 - Improper Protection of Alternate Path

Assigner

AMZN

References

2 references

URL	Tags
https://aws.amazon.com/security/security-bulletin…	vendor-advisory
https://pypi.org/project/awslabs.aws-api-mcp-serv…	patch

Impacted products

1 product

Vendor	Product	Version
AWS	AWS API MCP Server	Affected: 0.2.14 , < 1.3.9 (custom)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-4270",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-16T18:17:07.044936Z",
                "version": "2.0.3"
              },
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            }
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        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-16T18:17:17.927Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "AWS API MCP Server",
          "vendor": "AWS",
          "versions": [
            {
              "lessThan": "1.3.9",
              "status": "affected",
              "version": "0.2.14",
              "versionType": "custom"
            }
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      ],
      "descriptions": [
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            }
          ],
          "value": "Improper Protection of Alternate Path exists in the no-access and workdir feature of the AWS API MCP Server versions \u003e= 0.2.14 and \u003c 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.\n\nTo remediate this issue, users should upgrade to version 1.3.9."
        }
      ],
      "impacts": [
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          "descriptions": [
            {
              "lang": "en",
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            }
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        }
      ],
      "metrics": [
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            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
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            "valueDensity": "NOT_DEFINED",
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            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
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      "problemTypes": [
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          "descriptions": [
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      "providerMetadata": {
        "dateUpdated": "2026-03-16T16:17:11.659Z",
        "orgId": "ff89ba41-3aa1-4d27-914a-91399e9639e5",
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      "references": [
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          "url": "https://aws.amazon.com/security/security-bulletins/2026-007-AWS/"
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          ],
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    "datePublished": "2026-03-16T16:07:53.324Z",
    "dateReserved": "2026-03-16T14:28:58.998Z",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

PYSEC-2026-162

CVE-2026-4270 (GCVE-0-2026-4270)

Tags

Sightings

Nomenclature