Yes, this might be a security issue, especially if me.hochalla.aspx handler/page is not among the known files of your web application.
You may also search for me.hochalla.aspx in the app files and if it exists to examine its code which might give you any clues.
My advice is to upgrade your project to the latest version 2020.1.219 of Telerik.Web.UI.dll and to apply the recommended security keys. If they are already applied, create new ones since the original keys might be stolen from the compromised web.config file.
The latest version provides fixes for the following vulnerabilities:
You can find more information on how to secure your app in these articles:
Progress is here for your business, like always. Read more
about the measures we are taking to ensure business continuity and help fight the COVID-19 pandemic.
Our thoughts here at Progress are with those affected by the outbreak.