OPNsense through 20.1.5 contains an open redirect vulnerability via the url redirect parameter in the login page, which is not filtered. An attacker can redirect a user to a malicious site and possibly obtain sensitive information, modify data, and/or execute unauthorized operations.
View the template here CVE-2020-23015.yaml
References:
https://nvd.nist.gov/vuln/detail/CVE-2020-23015