Make regex stricter

Author: eXenon

cs_api_core/cs_api_core.ml

@@ -191,7 +191,7 @@ let parse_s3_signature_request ~body =
 
 let parse_s3_response ~body =
   try
-    let key_extractor = Str.regexp "<.*Key.*>\\([^<>]*\\)</.*Key.*>" in
+    let key_extractor = Str.regexp "<Key.*>\\([^<>]*\\)</Key>" in
     let _ = Str.search_forward key_extractor body 0 in
     Ok (Str.matched_group 1 body)
   with