diff --git a/litellm/llms/bedrock/batches/transformation.py b/litellm/llms/bedrock/batches/transformation.py
index 5d008038ca..0602b1c2f6 100644
--- a/litellm/llms/bedrock/batches/transformation.py
+++ b/litellm/llms/bedrock/batches/transformation.py
@@ -1,4 +1,5 @@
 import os
+import re
 import time
 from typing import Any, Dict, List, Literal, Optional, Union, cast
 
@@ -294,7 +295,8 @@ class BedrockBatchesConfig(BaseAWSLLM, BaseBatchesConfig):
             raise ValueError(f"Invalid ARN format: {batch_id}")
 
         region = arn_parts[3]
-        # arn_parts[5] contains "model-invocation-job/{jobId}"
+        if not re.match(r"^[a-z][a-z0-9-]*$", region):
+            raise ValueError(f"Invalid region in ARN: {batch_id}")
 
         # Build the endpoint URL for GetModelInvocationJob
         # AWS API format: GET /model-invocation-job/{jobIdentifier}
diff --git a/litellm/llms/s3_vectors/vector_stores/transformation.py b/litellm/llms/s3_vectors/vector_stores/transformation.py
index 11836e361e..19b5976986 100644
--- a/litellm/llms/s3_vectors/vector_stores/transformation.py
+++ b/litellm/llms/s3_vectors/vector_stores/transformation.py
@@ -1,3 +1,4 @@
+import re
 from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple, Union
 
 import httpx
@@ -66,6 +67,8 @@ class S3VectorsVectorStoreConfig(BaseVectorStoreConfig, BaseAWSLLM):
         aws_region_name = litellm_params.get("aws_region_name")
         if not aws_region_name:
             raise ValueError("aws_region_name is required for S3 Vectors")
+        if not re.match(r"^[a-z][a-z0-9-]*$", aws_region_name):
+            raise ValueError("Invalid aws_region_name format")
         return f"https://s3vectors.{aws_region_name}.api.aws"
 
     def transform_search_vector_store_request(
diff --git a/litellm/llms/snowflake/utils.py b/litellm/llms/snowflake/utils.py
index 9d458f6ece..d84efdd9fc 100644
--- a/litellm/llms/snowflake/utils.py
+++ b/litellm/llms/snowflake/utils.py
@@ -1,3 +1,4 @@
+import re
 from typing import TYPE_CHECKING, Any, List, Optional, Tuple
 
 from litellm.secret_managers.main import get_secret_str
@@ -61,6 +62,8 @@ class SnowflakeBaseConfig:
                 account_id = get_secret_str("SNOWFLAKE_ACCOUNT_ID")
             if account_id is None:
                 raise ValueError("Missing snowflake account_id")
+            if not re.match(r"^[a-zA-Z0-9_-]+$", account_id):
+                raise ValueError("Invalid account_id format")
             api_base = f"https://{account_id}.snowflakecomputing.com/api/v2"
 
         api_base = api_base.rstrip("/")
diff --git a/litellm/llms/vertex_ai/common_utils.py b/litellm/llms/vertex_ai/common_utils.py
index 43e77f4fb7..c13f6a86f8 100644
--- a/litellm/llms/vertex_ai/common_utils.py
+++ b/litellm/llms/vertex_ai/common_utils.py
@@ -232,8 +232,11 @@ def get_vertex_base_url(
     """
     if vertex_location == "global":
         return "https://aiplatform.googleapis.com"
-    else:
-        return f"https://{vertex_location}-aiplatform.googleapis.com"
+    if vertex_location is not None and not re.match(
+        r"^[a-z][a-z0-9-]*$", vertex_location
+    ):
+        raise ValueError("Invalid vertex_location format")
+    return f"https://{vertex_location}-aiplatform.googleapis.com"
 
 
 def _get_embedding_url(
diff --git a/litellm/proxy/pass_through_endpoints/llm_passthrough_endpoints.py b/litellm/proxy/pass_through_endpoints/llm_passthrough_endpoints.py
index 1ef866486e..3cf155739c 100644
--- a/litellm/proxy/pass_through_endpoints/llm_passthrough_endpoints.py
+++ b/litellm/proxy/pass_through_endpoints/llm_passthrough_endpoints.py
@@ -8,6 +8,7 @@ Use litellm with Anthropic SDK, Vertex AI SDK, Cohere SDK, etc.
 
 import json
 import os
+import re
 from typing import Any, Optional, Tuple, Union, cast
 
 import httpx
@@ -1500,6 +1501,10 @@ def get_vertex_base_url(vertex_location: Optional[str]) -> str:
     """
     if vertex_location == "global":
         return "https://aiplatform.googleapis.com/"
+    if vertex_location is not None and not re.match(
+        r"^[a-z][a-z0-9-]*$", vertex_location
+    ):
+        raise ValueError("Invalid vertex_location format")
     return f"https://{vertex_location}-aiplatform.googleapis.com/"