{"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_01M5KEW9TBQW73KH07P32N6K8J","modified_at":"2026-07-16T18:45:48.199122861Z","published_at":"2025-07-04T22:06:49Z","references":["https://osv.dev/vulnerability/GHSA-3qhf-m339-9g5v","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/advisories/GHSA-3qhf-m339-9g5v","https://github.com/modelcontextprotocol/python-sdk","https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.9.4","https://github.com/pypa/advisory-database/tree/main/vulns/mcp/PYSEC-2026-1616.yaml","https://pypi.org/project/mcp"],"severity":{"label":"high","score":8.7},"sources":[{"source":"osv","source_id":"GHSA-3qhf-m339-9g5v","url":"https://osv.dev/vulnerability/GHSA-3qhf-m339-9g5v"},{"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"}