There is no such thing according to Peder Sjölander, IT Director at the Swedish Tax Agency:

https://www.svt.se/nyheter/inrikes/uppgift-statlig-it-inform...

– Neither our data nor our users' data has been leaked. It is a service we use for e-signatures that has been affected, but there is no data from us or our users there, says

The information that source code was leaked from a joint government e-platform is not true, according to Peder Sjölander.

– There is no such platform. I think the perpetrators in this want people to feel insecure. We feel confident that our data is safe and we have the situation under control before the tax return period opens next week.