fix(proxy): mask default_litellm_params secrets for non-admin callers of /get/config/callbacks

default_litellm_params is merged into every completion call's kwargs, so an
operator can put a shared api_key or an Authorization header under
extra_headers there. Router.get_settings() now returns it (needed so the
Admin UI's Router Settings page can display/edit it), but /get/config/callbacks
forwarded router_settings verbatim regardless of caller role - unlike the
callback and alerting env vars on the same response, which already redact for
non-full-admin callers (e.g. PROXY_ADMIN_VIEW_ONLY). That let a read-only
admin read another admin's upstream provider credentials.

Add the same role gate used for callback/alerting env vars, scoped to
default_litellm_params via the existing SensitiveDataMasker so any
key/secret/token/auth-shaped field is masked for non-full-admin callers while
full admins keep seeing the real value.

litellm/proxy/proxy_server.py

@@ -14620,6 +14620,23 @@ def _apply_webhook_role_gate(webhook_map, is_full_admin: bool):
     return {alert_type: "REDACTED" for alert_type in webhook_map}
 
 
+def _apply_router_settings_role_gate(router_settings: dict, is_full_admin: bool) -> dict:
+    """
+    ``default_litellm_params`` is an open-ended kwargs dict (Router merges it into
+    every completion call), so an admin can put a shared ``api_key`` or an
+    ``extra_headers`` Authorization token there. Unlike the other fields on
+    this page, nothing else masks it before it reaches non-full-admin callers
+    of /get/config/callbacks.
+    """
+    default_litellm_params = router_settings.get("default_litellm_params")
+    if is_full_admin or not isinstance(default_litellm_params, dict):
+        return router_settings
+    return {
+        **router_settings,
+        "default_litellm_params": SENSITIVE_DATA_MASKER.mask_dict(default_litellm_params),
+    }
+
+
 @router.get(
     "/config/field/info",
     tags=["config.yaml"],
@@ -15224,7 +15241,7 @@ async def get_config(
         if llm_router is None:
             _router_settings = {}
         else:
-            _router_settings = llm_router.get_settings()
+            _router_settings = _apply_router_settings_role_gate(llm_router.get_settings(), is_full_admin)
 
         return {
             "status": "success",

tests/test_litellm/proxy/test_proxy_server.py

@@ -924,6 +924,62 @@ def test_get_config_custom_callback_api_env_vars(monkeypatch):
     }
 
 
+def _get_config_with_default_litellm_params(monkeypatch, user_role):
+    """
+    default_litellm_params is merged into every completion call, so an admin
+    can put a shared api_key/extra_headers Authorization token there. Router
+    exposes it verbatim via get_settings(); /get/config/callbacks must not
+    forward that verbatim to callers who aren't full proxy admins.
+    """
+    from litellm.proxy.proxy_server import app, proxy_config, user_api_key_auth
+
+    mock_router = MagicMock()
+    mock_router.get_settings.return_value = {
+        "default_litellm_params": {
+            "api_key": "sk-super-secret-upstream-key",
+            "timeout": 30,
+        },
+    }
+    monkeypatch.setattr("litellm.proxy.proxy_server.llm_router", mock_router)
+    monkeypatch.setattr(
+        proxy_config,
+        "get_config",
+        AsyncMock(return_value={"litellm_settings": {}, "general_settings": {}, "environment_variables": {}}),
+    )
+
+    original_overrides = app.dependency_overrides.copy()
+    app.dependency_overrides[user_api_key_auth] = lambda: UserAPIKeyAuth(
+        user_role=user_role, api_key="sk-1234"
+    )
+
+    client = TestClient(app)
+    try:
+        return client.get("/get/config/callbacks")
+    finally:
+        app.dependency_overrides = original_overrides
+
+
+def test_get_config_masks_default_litellm_params_secrets_for_non_admin(monkeypatch):
+    response = _get_config_with_default_litellm_params(
+        monkeypatch, LitellmUserRoles.PROXY_ADMIN_VIEW_ONLY
+    )
+
+    assert response.status_code == 200
+    default_litellm_params = response.json()["router_settings"]["default_litellm_params"]
+    assert "sk-super-secret-upstream-key" not in json.dumps(default_litellm_params)
+    # non-sensitive keys are unaffected
+    assert default_litellm_params["timeout"] == 30
+
+
+def test_get_config_returns_default_litellm_params_unmasked_for_full_admin(monkeypatch):
+    response = _get_config_with_default_litellm_params(monkeypatch, LitellmUserRoles.PROXY_ADMIN)
+
+    assert response.status_code == 200
+    default_litellm_params = response.json()["router_settings"]["default_litellm_params"]
+    assert default_litellm_params["api_key"] == "sk-super-secret-upstream-key"
+    assert default_litellm_params["timeout"] == 30
+
+
 def test_get_config_returns_email_settings(monkeypatch):
     """
     Regression for https://github.com/BerriAI/litellm/issues/19221