CVE-2021-21705

A flaw was found in php. Currently, php’s FILTER_VALIDATE_URL check doesn’t recognize some non-compliant RFC 3986 URLs and returns them as valid. This flaw allows an attacker to craft URLs, which depending on how the URL filter checking is used on the application side, lead to Server Side Request Forgery. This issue presents an integrity risk for the application, as eventually, the attacker can manipulate resources that shouldn’t be fully available for users.