Stop Spammers Security <= 2022.5 - Unauthenticated PHP Object Injection

The Stop Spammers Security plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including, 2022.5 via deserialization of untrusted input when issuing a CPATCHA challenge. This allows unauthenticated attackers to inject a PHP Object. No POP chain is present in the vulnerable plugin. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code. Note: The official PHP recommendation is not to pass untrusted input to unserialize even if the allowed_classes option is set to false.