diff --git a/litellm/__init__.py b/litellm/__init__.py
index e45d926e8db..d88e1bffb32 100644
--- a/litellm/__init__.py
+++ b/litellm/__init__.py
@@ -164,7 +164,8 @@ initialized_langfuse_clients: int = 0
 langfuse_default_tags: Optional[List[str]] = None
 langsmith_batch_size: Optional[int] = None
 prometheus_initialize_budget_metrics: Optional[bool] = False
-require_auth_for_metrics_endpoint: Optional[bool] = False
+# SECURITY FIX: Default to True to prevent unauthenticated PII exposure (#24530)
+require_auth_for_metrics_endpoint: Optional[bool] = True
 argilla_batch_size: Optional[int] = None
 datadog_use_v1: Optional[bool] = False  # if you want to use v1 datadog logged payload.
 gcs_pub_sub_use_v1: Optional[