diff --git a/litellm/proxy/_experimental/mcp_server/openapi_to_mcp_generator.py b/litellm/proxy/_experimental/mcp_server/openapi_to_mcp_generator.py
index 6ab7d5956b9..6f945c2448a 100644
--- a/litellm/proxy/_experimental/mcp_server/openapi_to_mcp_generator.py
+++ b/litellm/proxy/_experimental/mcp_server/openapi_to_mcp_generator.py
@@ -28,6 +28,7 @@ from litellm.proxy._experimental.mcp_server.exceptions import (
 # which include '/'. Sanitize here so the same regex passes everywhere downstream.
 _OPENAPI_TOOL_NAME_INVALID_CHARS: Final = re.compile(r"[^a-zA-Z0-9_-]")
 _OPENAPI_TOOL_NAME_MAX_LEN: Final = 128
+_MAX_YAML_INT_LENGTH: Final = 1024
 
 
 def sanitize_openapi_tool_name(raw_name: str) -> str:
@@ -171,6 +172,7 @@ def _parse_openapi_spec(text: str) -> Mapping[str, Any]:
         parsed: Any = json.loads(text)
     except json.JSONDecodeError:
         import yaml
+        from yaml.nodes import ScalarNode
 
         class _NoMergeSafeLoader(yaml.SafeLoader):
             def compose_node(self, parent: object, index: object) -> object:
@@ -184,6 +186,16 @@ def _parse_openapi_spec(text: str) -> Mapping[str, Any]:
                     raise yaml.YAMLError("YAML merge keys are not supported")
                 super().flatten_mapping(node)
 
+            def construct_yaml_int(self, node: ScalarNode) -> int:
+                if len(node.value) > _MAX_YAML_INT_LENGTH:
+                    raise yaml.YAMLError("YAML integer is too long")
+                return super().construct_yaml_int(node)
+
+        _NoMergeSafeLoader.add_constructor(
+            "tag:yaml.org,2002:int",
+            _NoMergeSafeLoader.construct_yaml_int,
+        )
+
         parsed = yaml.load(text, Loader=_NoMergeSafeLoader)
 
     if not isinstance(parsed, dict):
diff --git a/tests/unit/proxy/_experimental/mcp_server/test_openapi_to_mcp_generator.py b/tests/unit/proxy/_experimental/mcp_server/test_openapi_to_mcp_generator.py
index 5253d0653c0..5f5b8e438af 100644
--- a/tests/unit/proxy/_experimental/mcp_server/test_openapi_to_mcp_generator.py
+++ b/tests/unit/proxy/_experimental/mcp_server/test_openapi_to_mcp_generator.py
@@ -347,6 +347,14 @@ components:
         )
 
 
+def test_parse_openapi_spec_rejects_oversized_yaml_integer() -> None:
+    import yaml
+
+    oversized_integer: Final = "1" + ":11" * gen._MAX_YAML_INT_LENGTH
+    with pytest.raises(yaml.YAMLError, match="YAML integer is too long"):
+        gen._parse_openapi_spec(f"openapi: 3.0.0\nx-expensive: {oversized_integer}\n")
+
+
 def _create_mock_client(method: str, response_text: str, status_code: int = 200) -> AsyncMock:
     """Utility to create a mocked async httpx client for the given method.