Python: Percent-encode path parameter values in RestApiOperation.build_path

python/semantic_kernel/connectors/openapi_plugin/models/rest_api_operation.py

@@ -2,7 +2,7 @@
 
 import re
 from typing import Any, Final
-from urllib.parse import ParseResult, ParseResultBytes, urlencode, urljoin, urlparse, urlunparse
+from urllib.parse import ParseResult, ParseResultBytes, quote, urlencode, urljoin, urlparse, urlunparse
 
 from semantic_kernel.connectors.openapi_plugin.models.rest_api_expected_response import (
     RestApiExpectedResponse,
@@ -288,7 +288,7 @@ def build_path(self, path_template: str, arguments: dict[str, Any]) -> str:
                         f"required parameter of the operation - `{self.id}`."
                     )
                 continue
-            path_template = path_template.replace(f"{{{parameter.name}}}", str(argument))
+            path_template = path_template.replace(f"{{{parameter.name}}}", quote(str(argument), safe=""))
         return path_template
 
     def build_query_string(self, arguments: dict[str, Any]) -> str:

python/tests/unit/connectors/openapi_plugin/test_sk_openapi.py

@@ -412,6 +412,34 @@ def test_build_path_with_optional_and_required_parameters():
     assert operation.build_path(operation.path, arguments) == expected_path
 
 
+def test_build_path_encodes_special_characters():
+    parameters = [RestApiParameter(name="id", type="string", location=RestApiParameterLocation.PATH, is_required=True)]
+    operation = RestApiOperation(
+        id="test", method="GET", servers=["https://example.com/"], path="/resource/{id}", params=parameters
+    )
+    # Characters like /, ?, #, and spaces must be percent-encoded to prevent traversal
+    arguments = {"id": "foo/bar?q=1#frag data"}
+    result = operation.build_path(operation.path, arguments)
+    encoded_part = result.split("/resource/")[1]
+    assert "/" not in encoded_part
+    assert "?" not in encoded_part
+    assert "#" not in encoded_part
+    assert " " not in encoded_part
+    # Python's quote(safe="") encodes all except unreserved chars (letters, digits, _, ., -, ~)
+    assert result == "/resource/foo%2Fbar%3Fq%3D1%23frag%20data"
+
+
+def test_build_path_prevents_path_traversal():
+    parameters = [RestApiParameter(name="id", type="string", location=RestApiParameterLocation.PATH, is_required=True)]
+    operation = RestApiOperation(
+        id="test", method="GET", servers=["https://example.com/"], path="/resource/{id}", params=parameters
+    )
+    arguments = {"id": "../../admin"}
+    result = operation.build_path(operation.path, arguments)
+    # The slashes must be encoded so ../../admin becomes a single path segment, not a traversal
+    assert result == "/resource/..%2F..%2Fadmin"
+
+
 def test_build_query_string_with_required_parameter():
     parameters = [
         RestApiParameter(name="query", type="string", location=RestApiParameterLocation.QUERY, is_required=True)