Uncaught exception in MCP Python SDK - CVE-2025-53365
Published: December 18, 2025
Vulnerability identifier: #VU120188
CSH Severity: Medium
CVSS v4.0: 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:U/U:Green
CVE-ID: CVE-2025-53365
CWE-ID: CWE-248
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Model Context Protocol
Affected software:
MCP Python SDK
MCP Python SDK
Detailed vulnerability description
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to an unhandled exception when a client deliberately triggers an exception after establishing a streamable HTTP session. A remote attacker can crash the server.
How to mitigate CVE-2025-53365
Install updates from vendor's website.