{"action":"Upgrade mcp to 1.9.4 or later.","affected":[{"fixed":"1.9.4","introduced":"0"}],"component":"mcp","cve_ids":["CVE-2025-53366"],"ecosystem":"PyPI","epss":0.09754,"exploited":false,"fixed_versions":["1.9.4"],"ghsa_id":"GHSA-3qhf-m339-9g5v","id":"tcs_01M5KGTNE0V2DEQZ65C8PSS7NF","modified_at":"2026-07-07T17:47:03.420621263Z","published_at":"2026-07-07T16:02:56.172263Z","references":["https://osv.dev/vulnerability/PYSEC-2026-1616","https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-3qhf-m339-9g5v","https://nvd.nist.gov/vuln/detail/CVE-2025-53366","https://github.com/modelcontextprotocol/python-sdk/pull/822","https://github.com/modelcontextprotocol/python-sdk/commit/29c69e6a47d0104d0afcea6ac35e7ab02fde809a","https://github.com/modelcontextprotocol/python-sdk","https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.9.4","https://pypi.org/project/mcp","https://github.com/advisories/GHSA-3qhf-m339-9g5v"],"severity":{"label":"high","score":8.7},"sources":[{"source":"osv","source_id":"PYSEC-2026-1616","url":"https://osv.dev/vulnerability/PYSEC-2026-1616"},{"source":"nvd","source_id":"CVE-2025-53366","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-53366"}],"summary":"MCP Python SDK vulnerability in the FastMCP Server causes validation error, leading to DoS"}