I renamed all occurrences of SetCookie to a more narrow naming. So the error in the console is not there anymore. Nevertheless, the error is still there. I also checked on English Wikisource, there is the same error, so I also guess this is a duplicate of T297338.

Thanks for the fix. I stumpled over this problem yesterday as it also affects the ItemPage.removeClaims function. I appreciate that there is already a fix in place. Looking forward to the release ;-).

It disappeared. Thanks for the hints.

I thank you a lot. That was fast.

Thanks for the fast response. I have two parameter (1 and 2) in a template which activate under special circumstances several features. the {{#if ... statement for checking this two parameter is quite long. So I want to calculate a new local variable 3 out of 1 and 2 and use this parameter in further {{#if:... occurences in the template. So I want to do exactly what the extension would do. But I'm happy to use another workaround. To put the complete Template in a Lua Modul is not very ideal.

Thanks for the explaination

problematic code was deleted

We will trigger a request for deletion of https://de.wikisource.org/wiki/Vorlage:ExtImage. This should be the only template which uses the vulnerable code.

How can we help. We need the tool running again.

@Bawolff: Are you going to repair the errors?

The error still exists. We followed the recommandation of @Tpt. we 're working to remove all of the Template-usage in the namespace Seite. At this Lemma
this already happened. After deleting the template here, the error stillt exists.

@matmarex: Thanks for your help. I applied your suggestions. This fix the big red errors for the moment. But still is there an error in the cite extension in my opinion.

This Error cause a lot of trouble in de.wikisource. It isn't possible for us to avoid these errors.