Vulnerability-Lookup

GHSA-J975-95F5-7WQH

Vulnerability from github – Published: 2025-07-04 22:06 – Updated: 2026-07-16 18:30

Summary

MCP Python SDK has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service

Details

If a client deliberately triggers an exception after establishing a streamable HTTP session, this can lead to an uncaught ClosedResourceError on the server side, causing the server to crash and requiring a restart to restore service. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures.

Thank you to Rich Harang for reporting this issue.

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

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "mcp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.10.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-53365"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-07-04T22:06:31Z",
    "nvd_published_at": "2025-07-04T22:15:22Z",
    "severity": "HIGH"
  },
  "details": "If a client deliberately triggers an exception after establishing a streamable HTTP session, this can lead to an uncaught ClosedResourceError on the server side, causing the server to crash and requiring a restart to restore service. 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-j975-95f5-7wqh",
  "modified": "2026-07-16T18:30:53Z",
  "published": "2025-07-04T22:06:31Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-j975-95f5-7wqh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-53365"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/pull/967"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/commit/7b420656de48cfdb90b39eb582e60b6d55c2f891"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-j975-95f5-7wqh"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/modelcontextprotocol/python-sdk"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.10.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/mcp/PYSEC-2026-1618.yaml"
    },
    {
      "type": "WEB",
      "url": "https://pypi.org/project/mcp"
    }
  ],
  "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 has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service"
}

CVE-2025-53365 (GCVE-0-2025-53365)

Vulnerability from cvelistv5 – Published: 2025-07-04 22:03 – Updated: 2025-07-08 13:53

Title

MCP Python SDK has Unhandled Exception in Streamable HTTP Transport ,Leading to Denial of Service

Summary

The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to version 1.10.0, if a client deliberately triggers an exception after establishing a streamable HTTP session, this can lead to an uncaught ClosedResourceError on the server side, causing the server to crash and requiring a restart to restore service. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures. Version 1.10.0 contains a patch for the issue.

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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-07-08 13:53 UTC

CWE

CWE-248 - Uncaught Exception

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/modelcontextprotocol/python-sd…	x_refsource_CONFIRM
https://github.com/modelcontextprotocol/python-sd…	x_refsource_MISC
https://github.com/modelcontextprotocol/python-sd…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
modelcontextprotocol	python-sdk	Affected: < 1.10.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-53365",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-07-08T13:53:26.324368Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-07-08T13:53:36.518Z",
          "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 1.10.0"
            }
          ]
        }
      ],
      "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 1.10.0, if a client deliberately triggers an exception after establishing a streamable HTTP session, this can lead to an uncaught ClosedResourceError on the server side, causing the server to crash and requiring a restart to restore service. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures. Version 1.10.0 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": "2025-07-04T22:03:46.893Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-j975-95f5-7wqh",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-j975-95f5-7wqh"
        },
        {
          "name": "https://github.com/modelcontextprotocol/python-sdk/pull/967",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/modelcontextprotocol/python-sdk/pull/967"
        },
        {
          "name": "https://github.com/modelcontextprotocol/python-sdk/commit/7b420656de48cfdb90b39eb582e60b6d55c2f891",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/modelcontextprotocol/python-sdk/commit/7b420656de48cfdb90b39eb582e60b6d55c2f891"
        }
      ],
      "source": {
        "advisory": "GHSA-j975-95f5-7wqh",
        "discovery": "UNKNOWN"
      },
      "title": "MCP Python SDK has Unhandled Exception in Streamable HTTP Transport ,Leading to Denial of Service"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-53365",
    "datePublished": "2025-07-04T22:03:46.893Z",
    "dateReserved": "2025-06-27T12:57:16.121Z",
    "dateUpdated": "2025-07-08T13:53:36.518Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

PYSEC-2026-1618

Vulnerability from pysec - Published: 2026-07-07 16:02 - Updated: 2026-07-07 17:24

Details

Thank you to Rich Harang for reporting this issue.

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

Impacted products

Name	purl
mcp	pkg:pypi/mcp

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "mcp",
        "purl": "pkg:pypi/mcp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.10.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.9.1",
        "1.0.0",
        "1.1.0",
        "1.1.1",
        "1.1.2",
        "1.1.3",
        "1.2.0",
        "1.2.0rc1",
        "1.2.1",
        "1.3.0",
        "1.3.0rc1",
        "1.4.0",
        "1.4.1",
        "1.5.0",
        "1.6.0",
        "1.7.0",
        "1.7.1",
        "1.8.0",
        "1.8.1",
        "1.9.0",
        "1.9.1",
        "1.9.2",
        "1.9.3",
        "1.9.4"
      ]
    }
  ],
  "aliases": [
    "CVE-2025-53365",
    "GHSA-j975-95f5-7wqh"
  ],
  "details": "If a client deliberately triggers an exception after establishing a streamable HTTP session, this can lead to an uncaught ClosedResourceError on the server side, causing the server to crash and requiring a restart to restore service. 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": "PYSEC-2026-1618",
  "modified": "2026-07-07T17:24:40.321367Z",
  "published": "2026-07-07T16:02:56.105116Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-j975-95f5-7wqh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-53365"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/pull/967"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/commit/7b420656de48cfdb90b39eb582e60b6d55c2f891"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/modelcontextprotocol/python-sdk"
    },
    {
      "type": "WEB",
      "url": "https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.10.0"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/mcp"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-j975-95f5-7wqh"
    }
  ],
  "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 has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

GHSA-J975-95F5-7WQH

CVE-2025-53365 (GCVE-0-2025-53365)

PYSEC-2026-1618

Tags

Sightings

Nomenclature

Related by attack behaviour