add_query_arg() and remove_query_arg()

Looks like formidable uses at least one of these functions:

add_query_arg() and remove_query_arg()

Had formidable been looked at to make sure it’s not vulnerable to this issue:
https://blog.sucuri.net/2015/04/security-advisory-xss-vulnerability-affecting-multiple-wordpress-plugins.html

https://ww.wp.xz.cn/plugins/formidable/