Index: ChapterX.Application/Comment/Commands/UpdateHandler.cs
===================================================================
--- ChapterX.Application/Comment/Commands/UpdateHandler.cs	(revision 877c13c3dd0934c1d31da7988d0d2c2c5925ed55)
+++ ChapterX.Application/Comment/Commands/UpdateHandler.cs	(revision 99c1e45f4ac45a164229bc6f60f3b05bc26df047)
@@ -22,4 +22,7 @@
                 return new UpdateResponse(false);
 
+            if (comment.UserId != request.CallerId)
+                throw new UnauthorizedAccessException("You do not own this comment.");
+
             comment.Content = request.Content;
             comment.UpdatedAt = DateTime.UtcNow;