diff --git a/validation/src/validator.rs b/validation/src/validator.rs
index e5ef087..7912b99 100644
--- a/validation/src/validator.rs
+++ b/validation/src/validator.rs
@@ -34,6 +34,12 @@ fn hash_source(source:&str)->String{
 #[allow(dead_code)]
 #[derive(Debug)]
 pub enum Error{
+	ModelInfoDownload(rbx_asset::cloud::GetError),
+	CreatorTypeMustBeUser,
+	RevisionMismatch{
+		current:u64,
+		submitted:u64,
+	},
 	ScriptFlaggedIllegalKeyword(String),
 	ScriptBlocked(Option<submissions_api::types::ScriptID>),
 	ScriptNotYetReviewed(Option<submissions_api::types::ScriptID>),
@@ -90,6 +96,24 @@ impl From<crate::nats_types::ValidateSubmissionRequest> for ValidateRequest{
 
 impl crate::message_handler::MessageHandler{
 	pub async fn validate_inner(&self,validate_info:ValidateRequest)->Result<(),Error>{
+		// discover asset creator and latest version
+		let info=self.cloud_context.get_asset_info(
+			rbx_asset::cloud::GetAssetLatestRequest{asset_id:validate_info.ModelID}
+		).await.map_err(Error::ModelInfoDownload)?;
+
+		// reject models created by a group
+		let rbx_asset::cloud::Creator::userId(_user_id)=info.creationContext.creator else{
+			return Err(Error::CreatorTypeMustBeUser);
+		};
+
+		// Has the map been updated since it was submitted?
+		if info.revisionId!=validate_info.ModelVersion{
+			return Err(Error::RevisionMismatch{
+				current:info.revisionId,
+				submitted:validate_info.ModelVersion,
+			});
+		}
+
 		// download the map model
 		let maybe_gzip=download_asset_version(&self.cloud_context,rbx_asset::cloud::GetAssetVersionRequest{
 			asset_id:validate_info.ModelID,