Vulnerability scanning SaaS service is online 3-rd generation vulnerability scanner with scheduled assessments and vulnerability subscription. You can use service to check security of your network perimeter.
About zero-day vulnerabilities
Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.
Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.