URL Validator does not work with Protocol-relative URLs · Issue #59 · jbowens/jBBCode · GitHub
XSS in Limited Input Formats - Brute XSS
টুইটারে Mike Oram: "@emma_train_ The FILTER_VALIDATE_URL part is one of the built in patterns that PHP has, it's actually a PHP global constant that contains the pattern. A list of available filters
filter_ Var function defect (CTF example, with source code)
filter_var + FILTER_VALIDATE_URL mode too restrictive for url parsing · Issue #330 · onelogin/php-saml · GitHub