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fix: validate wildcard port allowlist suffixes #2812

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fix: validate wildcard port allowlist suffixes #2812

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8 changes: 4 additions & 4 deletions src/mcp/server/transport_security.py
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Original file line number Diff line number Diff line change
Expand Up @@ -55,8 +55,8 @@ def _validate_host(self, host: str | None) -> bool:
if allowed.endswith(":*"):
# Extract base host from pattern
base_host = allowed[:-2]
# Check if the actual host starts with base host and has a port
if host.startswith(base_host + ":"):
# Check if the actual host is base host plus a numeric port.
if host.startswith(base_host + ":") and host[len(base_host) + 1 :].isdigit():
return True

logger.warning(f"Invalid Host header: {host}")
Expand All @@ -77,8 +77,8 @@ def _validate_origin(self, origin: str | None) -> bool:
if allowed.endswith(":*"):
# Extract base origin from pattern
base_origin = allowed[:-2]
# Check if the actual origin starts with base origin and has a port
if origin.startswith(base_origin + ":"):
# Check if the actual origin is base origin plus a numeric port.
if origin.startswith(base_origin + ":") and origin[len(base_origin) + 1 :].isdigit():
return True

logger.warning(f"Invalid Origin header: {origin}")
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4 changes: 4 additions & 0 deletions tests/server/test_transport_security.py
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Expand Up @@ -31,10 +31,14 @@ def _request(host: str | None, origin: str | None, content_type: str | None = "a
pytest.param(None, None, 421, id="missing-host"),
pytest.param("evil.example", None, 421, id="host-no-match"),
pytest.param("evil.example:9000", None, 421, id="host-wildcard-base-mismatch"),
pytest.param("wild.example:9000.evil", None, 421, id="host-wildcard-port-suffix"),
pytest.param("wild.example:notaport", None, 421, id="host-wildcard-nonnumeric-port"),
pytest.param("good.example", None, None, id="host-exact-no-origin"),
pytest.param("wild.example:9000", None, None, id="host-wildcard-match"),
pytest.param("good.example", "http://evil.example", 403, id="origin-no-match"),
pytest.param("good.example", "http://evil.example:9000", 403, id="origin-wildcard-base-mismatch"),
pytest.param("good.example", "http://wild.example:9000.evil", 403, id="origin-wildcard-port-suffix"),
pytest.param("good.example", "http://wild.example:notaport", 403, id="origin-wildcard-nonnumeric-port"),
pytest.param("good.example", "http://good.example", None, id="origin-exact"),
pytest.param("good.example", "http://wild.example:9000", None, id="origin-wildcard-match"),
],
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