{"items":[{"id":"NVI-00009062","kind":"vulnerability","title":"FastMCP OpenAPI Provider has an SSRF & Path Traversal Vulnerability","revision":2,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-vv7q-7jx5-f767","CVE-2026-32871"],"plain_summary":"GitHub lists this reviewed advisory for fastmcp. 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-21f2d65e0da1a7283f1c9ce27a252d44"],"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":"2026-10-27T16:40:35.000Z","value":"10 critical","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-9774131b501b042635c525ce6529393a"},{"kind":"EPSS","as_of":"2026-10-31T12:00:27.000Z","value":"0.925%","meaning":"FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.60464. Missing scores are unknown.","source_id":"sr-21f2d65e0da1a7283f1c9ce27a252d44"}],"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-9774131b501b042635c525ce6529393a","url":"https://github.com/advisories/GHSA-vv7q-7jx5-f767","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-vv7q-7jx5-f767","publisher":"GitHub Advisory Database","observed_at":"2026-10-31T21:56:36.327Z"},{"id":"sr-21f2d65e0da1a7283f1c9ce27a252d44","url":"https://www.first.org/epss/data.html","basis":"official_catalog","notes":"FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.","title":"CVE-2026-32871","publisher":"FIRST EPSS","observed_at":"2026-10-31T22:06:15.377Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-9774131b501b042635c525ce6529393a"],"technology":"fastmcp","known_exclusions":[],"conditions_summary":"## Technical Description\n\nThe `OpenAPIProvider` in FastMCP exposes internal APIs to MCP clients by parsing OpenAPI specifications. The `RequestDirector` class is responsible for constructing HTTP requests to the backend service.\n\nA critical vulnerability exists in the `_build_url()` method. When an OpenAPI operation defines path parameters (e.g., `/api/v1/users/{user_id}`), the system directly substitutes parameter values into the URL template string **without URL-encoding**. Subsequently, `urllib.parse.urljoin()` resolves the final URL.\n\nSince `urljoin()` interprets `../` sequences as directory traversal, an attacker controlling a path parameter can perform path traversal attacks to escape the intended API prefix and access arbitrary backend endpoints. This results in **authenticated SSRF**, as requests are sent with the authorization headers configured in the MCP provider.\n\n---\n\n## Vulnerable Code\n\n**File:** `fastmcp/utilities/openapi/director.py`\n\n```python\ndef _build_url(\n    self, path_template: str, path_params: dict[str, Any], base_url: str\n) -> str:\n    # Direct string substitution without encoding\n    url_path = path_template\n    for param_name, param_value in path_params.","public_affected_ranges":["< 3.2.0"]}],"null_published_at":"2026-10-31T22:27:09.610Z","source_updated_at":"2026-10-27T16:40:35.000Z","source_disclosed_at":"2026-03-31T22:53:21.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.","null_first_observed_at":"2026-10-31T21:56:36.327Z"},{"id":"NVI-00009062","kind":"vulnerability","title":"FastMCP OpenAPI Provider has an SSRF & Path Traversal Vulnerability","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-vv7q-7jx5-f767","CVE-2026-32871"],"plain_summary":"GitHub lists this reviewed advisory for fastmcp. 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-9774131b501b042635c525ce6529393a"],"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":"2026-10-27T16:40:35.000Z","value":"10 critical","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-9774131b501b042635c525ce6529393a"}],"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-9774131b501b042635c525ce6529393a","url":"https://github.com/advisories/GHSA-vv7q-7jx5-f767","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-vv7q-7jx5-f767","publisher":"GitHub Advisory Database","observed_at":"2026-10-31T21:56:36.327Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-9774131b501b042635c525ce6529393a"],"technology":"fastmcp","known_exclusions":[],"conditions_summary":"## Technical Description\n\nThe `OpenAPIProvider` in FastMCP exposes internal APIs to MCP clients by parsing OpenAPI specifications. The `RequestDirector` class is responsible for constructing HTTP requests to the backend service.\n\nA critical vulnerability exists in the `_build_url()` method. When an OpenAPI operation defines path parameters (e.g., `/api/v1/users/{user_id}`), the system directly substitutes parameter values into the URL template string **without URL-encoding**. Subsequently, `urllib.parse.urljoin()` resolves the final URL.\n\nSince `urljoin()` interprets `../` sequences as directory traversal, an attacker controlling a path parameter can perform path traversal attacks to escape the intended API prefix and access arbitrary backend endpoints. This results in **authenticated SSRF**, as requests are sent with the authorization headers configured in the MCP provider.\n\n---\n\n## Vulnerable Code\n\n**File:** `fastmcp/utilities/openapi/director.py`\n\n```python\ndef _build_url(\n    self, path_template: str, path_params: dict[str, Any], base_url: str\n) -> str:\n    # Direct string substitution without encoding\n    url_path = path_template\n    for param_name, param_value in path_params.","public_affected_ranges":["< 3.2.0"]}],"null_published_at":"2026-10-31T22:13:31.272Z","source_updated_at":"2026-10-27T16:40:35.000Z","source_disclosed_at":"2026-03-31T22:53:21.000Z","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":"2026-10-31T21:56:36.327Z"}],"next_cursor":null,"snapshot_revision":"42594"}