In the previous post, I talked about how to use Firefox as default browser for Sccm Catalog access.
As I have encountered the same issue with an internal implementation of ServiceNow, I first thought that the workaround would be the same,
however in our environement NTLM authentication is being used instead of kerberos, so the entry is different:
Open about:config and confirm that you want to make changes
enter the fqdn of your server (without protocol), ie
You should now be able to connect directly to your ServiceNow instance without being prompted for a password.