{"items":[{"id":"NVI-00016093","kind":"vulnerability","title":"Model Context Protocol (MCP) Python SDK does not enable DNS rebinding protection by default","revision":2,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected.","NVD lastModified does not establish freshness of every associated CPE record."],"lifecycle":"active","identifiers":["GHSA-9h52-p55h-vw2f","CVE-2025-66416"],"plain_summary":"GitHub lists this reviewed advisory for mcp. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-366712e1e80130e16a732d5f159a7c0d"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"CVSS","as_of":"2026-10-18T18:10:00.100Z","value":"8.1 HIGH (3.1)","meaning":"nvd@nist.gov severity; no combined Null risk score.","source_id":"sr-366712e1e80130e16a732d5f159a7c0d"},{"kind":"CVSS","as_of":"2026-10-18T18:10:00.100Z","value":"7.6 HIGH (4.0)","meaning":"security-advisories@github.com severity; no combined Null risk score.","source_id":"sr-366712e1e80130e16a732d5f159a7c0d"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-1dfffc9a0013213891d41c49c7ee27a1","url":"https://github.com/advisories/GHSA-9h52-p55h-vw2f","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-9h52-p55h-vw2f","publisher":"GitHub Advisory Database","observed_at":"2026-11-04T09:59:26.779Z"},{"id":"sr-366712e1e80130e16a732d5f159a7c0d","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-66416","basis":"official_catalog","notes":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","title":"CVE-2025-66416","publisher":"NIST National Vulnerability Database","observed_at":"2026-11-06T15:14:24.735Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-1dfffc9a0013213891d41c49c7ee27a1"],"technology":"mcp","known_exclusions":[],"conditions_summary":"### Description\n\nThe Model Context Protocol (MCP) Python SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication using `FastMCP` with streamable HTTP or SSE transport, and has not configured `TransportSecuritySettings`, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances.\n\nNote that running HTTP-based MCP servers locally without authentication is not recommended per MCP security best practices. This issue does not affect servers using stdio transport.\n\nServers created via `FastMCP()` now have DNS rebinding protection enabled by default when the `host` parameter is `127.0.0.1` or `localhost`. Users are advised to update to version `1.23.0` to receive this automatic protection. Users with custom low-level server configurations using `StreamableHTTPSessionManager` or `SseServerTransport` directly should explicitly configure `TransportSecuritySettings` when running an u","public_affected_ranges":["< 1.23.0"]}],"null_published_at":"2026-11-07T18:43:12.103Z","source_updated_at":"2026-07-16T18:31:01.000Z","source_disclosed_at":"2025-12-02T16:52:08.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"Source facts changed; compare the preserved prior revision.","null_first_observed_at":"2026-11-04T09:59:26.779Z"},{"id":"NVI-00016093","kind":"vulnerability","title":"Model Context Protocol (MCP) Python SDK does not enable DNS rebinding protection by default","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-9h52-p55h-vw2f","CVE-2025-66416"],"plain_summary":"GitHub lists this reviewed advisory for mcp. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-1dfffc9a0013213891d41c49c7ee27a1"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-1dfffc9a0013213891d41c49c7ee27a1","url":"https://github.com/advisories/GHSA-9h52-p55h-vw2f","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-9h52-p55h-vw2f","publisher":"GitHub Advisory Database","observed_at":"2026-11-04T09:59:26.779Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-1dfffc9a0013213891d41c49c7ee27a1"],"technology":"mcp","known_exclusions":[],"conditions_summary":"### Description\n\nThe Model Context Protocol (MCP) Python SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication using `FastMCP` with streamable HTTP or SSE transport, and has not configured `TransportSecuritySettings`, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances.\n\nNote that running HTTP-based MCP servers locally without authentication is not recommended per MCP security best practices. This issue does not affect servers using stdio transport.\n\nServers created via `FastMCP()` now have DNS rebinding protection enabled by default when the `host` parameter is `127.0.0.1` or `localhost`. Users are advised to update to version `1.23.0` to receive this automatic protection. Users with custom low-level server configurations using `StreamableHTTPSessionManager` or `SseServerTransport` directly should explicitly configure `TransportSecuritySettings` when running an u","public_affected_ranges":["< 1.23.0"]}],"null_published_at":"2026-11-04T10:04:27.889Z","source_updated_at":"2026-07-16T18:31:01.000Z","source_disclosed_at":"2025-12-02T16:52:08.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-11-04T09:59:26.779Z"}],"next_cursor":null,"snapshot_revision":"42594"}