CVE-2025-53366

July 4, 2025, 10:15 p.m.

8.7
High

Description

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.

Product(s) Impacted

Vendor Product Versions
Mcp
  • Mcp
  • <1.9.4

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-248
Uncaught Exception
An exception is thrown from a function, but it is not caught.

*CPE(s)

Affected systems and software identified for this CVE.

Type Vendor Product Version Update Edition Language Software Edition Target Software Target Hardware Other Information
a mcp mcp <1.9.4 / / / / / / /

References

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

Tags

security-advisories@github.com
CWE-248
2025-07-04
CVE-2025-53366

CVSS Score

8.7 / 10

CVSS Data - 4.0

  • Attack Vector: NETWORK
  • Attack Complexity: LOW
  • Attack Requirements: NONE
  • Privileges Required: NONE
  • User Interaction: NONE
  • Scope:
  • Confidentiality Impact: NONE
  • Integrity Impact: NONE
  • Availability Impact: HIGH
  • Exploit Maturity: NOT_DEFINED

    • 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/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

    View Vector String

Timeline

Published: July 4, 2025, 10:15 p.m.
Last Modified: July 4, 2025, 10:15 p.m.

Status : Received

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

security-advisories@github.com

*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.