chore: clarify clientside credential cleanup

litellm/router.py

@@ -2379,7 +2379,11 @@ class Router:
         """
         dep_params = deployment.get("litellm_params", {}) or {}
         for key in clientside_credential_keys:
-            if kwargs.get(key) is None and dep_params.get(key) is not None:
+            if (
+                key in kwargs
+                and kwargs.get(key) is None
+                and dep_params.get(key) is not None
+            ):
                 kwargs.pop(key, None)
 
     def _update_kwargs_with_deployment(

litellm/router_utils/clientside_credential_handler.py

@@ -92,11 +92,10 @@ def get_dynamic_litellm_params(litellm_params: dict, request_kwargs: dict) -> di
     # don't forward the admin's organization / extra_body / region / token /
     # vertex / aws fields — those were meant for the original upstream.
     # Always drop the admin's value first, then write the caller's value back
-    # if they resupplied the field. The naive
-    # ``if field not in request_kwargs: pop`` shape lets a caller *echo* a
-    # field name (with any value, including an empty string) to keep the
-    # admin's value in ``litellm_params`` and have it forwarded to the
-    # redirected upstream.
+    # when they resupplied a concrete, non-None field value. The old
+    # ``if field not in request_kwargs: pop`` shape let a caller echo a
+    # field name to keep the admin's value in ``litellm_params`` and have
+    # it forwarded to the redirected upstream.
     if (
         request_kwargs.get("api_base") is not None
         or request_kwargs.get("base_url") is not None

tests/test_litellm/proxy/auth/test_auth_utils.py

@@ -811,11 +811,7 @@ class TestGetDynamicLitellmParamsClearsAdminConfigOnBaseOverride:
     def test_caller_resupplied_value_overrides_admin_value_on_base_override(self):
         # When the caller redirects ``api_base`` and *also* supplies their
         # own value for one of the admin fields (e.g. ``organization``),
-        # the caller's value must win — never the admin's. The naive
-        # ``if field not in request_kwargs: pop`` shape lets a caller echo
-        # the field name with any value (or empty string) to keep the
-        # admin's value forwarded, which is the exfiltration vector this
-        # test guards against.
+        # the caller's value must win — never the admin's.
         from litellm.router_utils.clientside_credential_handler import (
             get_dynamic_litellm_params,
         )
@@ -836,9 +832,9 @@ class TestGetDynamicLitellmParamsClearsAdminConfigOnBaseOverride:
         assert out["extra_body"] == {"attacker": "value"}
 
     def test_field_echo_does_not_preserve_admin_value(self):
-        # Regression: a caller that echoes an admin-config field name with
-        # an *empty* value (or any value) must not be able to keep the
-        # admin's value in ``litellm_params``.
+        # Regression: a caller that resupplies an admin-config field name
+        # with an empty value must not be able to keep the admin's value in
+        # ``litellm_params``.
         from litellm.router_utils.clientside_credential_handler import (
             get_dynamic_litellm_params,
         )