github - ghsa-3qhf-m339-9g5v

ghsa-3qhf-m339-9g5v

Vulnerability from github

Published

2025-07-04 22:06

Modified

2025-07-05 01:48

Severity ?

8.7 (High) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Summary

MCP Python SDK vulnerability in the FastMCP Server causes validation error, leading to DoS

Details

A validation error in the MCP SDK can cause an unhandled exception when processing malformed requests, resulting in service unavailability (500 errors) until manually restarted. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures.

Thank you to Rich Harang for reporting this issue.

Show details on source website

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "mcp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.9.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-53366"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-07-04T22:06:49Z",
    "nvd_published_at": "2025-07-04T22:15:22Z",
    "severity": "HIGH"
  },
  "details": "A validation error in the MCP SDK can cause an unhandled exception when processing malformed requests, resulting in service unavailability (500 errors) until manually restarted. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures.\n\nThank you to Rich Harang for reporting this issue.",
  "id": "GHSA-3qhf-m339-9g5v",
  "modified": "2025-07-05T01:48:36Z",
  "published": "2025-07-04T22:06:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-3qhf-m339-9g5v"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-53366"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/pull/822"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/commit/29c69e6a47d0104d0afcea6ac35e7ab02fde809a"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/modelcontextprotocol/python-sdk"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.9.4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "MCP Python SDK vulnerability in the FastMCP Server causes validation error, leading to DoS"
}

CVE-2025-53366 (GCVE-0-2025-53366)

Vulnerability from cvelistv5

Published

2025-07-04 22:05

Modified

2025-07-08 13:52

Severity ?

8.7 (High) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CWE

CWE-248 - Uncaught Exception

Summary

The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to version 1.9.4, a validation error in the MCP SDK can cause an unhandled exception when processing malformed requests, resulting in service unavailability (500 errors) until manually restarted. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures. Version 1.9.4 contains a patch for the issue.

References

▼	URL	Tags
	https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-3qhf-m339-9g5v	x_refsource_CONFIRM
	https://github.com/modelcontextprotocol/python-sdk/pull/822	x_refsource_MISC
	https://github.com/modelcontextprotocol/python-sdk/commit/29c69e6a47d0104d0afcea6ac35e7ab02fde809a	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	modelcontextprotocol	python-sdk	Version: < 1.9.4

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-53366",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-07-08T13:52:21.837694Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-07-08T13:52:28.447Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "python-sdk",
          "vendor": "modelcontextprotocol",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.9.4"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to version 1.9.4, a validation error in the MCP SDK can cause an unhandled exception when processing malformed requests, resulting in service unavailability (500 errors) until manually restarted. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures. Version 1.9.4 contains a patch for the issue."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-248",
              "description": "CWE-248: Uncaught Exception",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-07-04T22:05:02.975Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-3qhf-m339-9g5v",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-3qhf-m339-9g5v"
        },
        {
          "name": "https://github.com/modelcontextprotocol/python-sdk/pull/822",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/modelcontextprotocol/python-sdk/pull/822"
        },
        {
          "name": "https://github.com/modelcontextprotocol/python-sdk/commit/29c69e6a47d0104d0afcea6ac35e7ab02fde809a",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/modelcontextprotocol/python-sdk/commit/29c69e6a47d0104d0afcea6ac35e7ab02fde809a"
        }
      ],
      "source": {
        "advisory": "GHSA-3qhf-m339-9g5v",
        "discovery": "UNKNOWN"
      },
      "title": "MCP SDK Vulnerable to FastMCP Server Validation Error, Leading to Denial of Service"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-53366",
    "datePublished": "2025-07-04T22:05:02.975Z",
    "dateReserved": "2025-06-27T12:57:16.121Z",
    "dateUpdated": "2025-07-08T13:52:28.447Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
Confirmed: The vulnerability is confirmed from an analyst perspective.
Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
Patched: This vulnerability was successfully patched by the user reporting the sighting.
Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
Not confirmed: The user expresses doubt about the veracity of the vulnerability.
Not patched: This vulnerability was not successfully patched by the user reporting the sighting.

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