Password Protected < 2.7.12 - Unauthenticated Authorization Bypass via IP Address Spoofing

Description

The plugin is vulnerable to authorization bypass via IP address spoofing due to the plugin trusting client-controlled HTTP headers (such as X-Forwarded-For, HTTP_CLIENT_IP, and similar headers) to determine user IP addresses in the `pp_get_ip_address()` function when the "Use transients" feature is enabled. This makes it possible for attackers to bypass authorization by spoofing these headers with the IP address of a legitimately authenticated user, granted the "Use transients" option is enabled (non-default configuration) and the site is not behind a CDN or reverse proxy that overwrites these headers.