WP Photo Album Plus <= 9.3.02.002 - Authenticated (Custom+) Command Injection via 'value' Parameter (crop item) in update-photo AJAX Action

The WP Photo Album Plus plugin for WordPress is vulnerable to authenticated Command Injection in all versions up to, and including, 9.3.02.002 via the `value` parameter of the `update-photo` AJAX action. This is due to insufficient shell escaping within the `wppa_image_magick_a()` function, where the attacker-controlled `value` parameter is concatenated raw — without `escapeshellarg()` — into an ImageMagick command string before being passed to `exec()`; further, `wppa_decode()` actively restores percent-encoded shell metacharacters (e.g., `%26`→`&`, `%23`→`#`) rather than stripping them, allowing crafted payloads to survive sanitization and break out of the ImageMagick argument context. This makes it possible for authenticated attackers holding the plugin-defined `wppa_upload` capability to execute arbitrary operating-system commands as the web-server user, achieving full remote code execution on the underlying server. Exploitation requires ImageMagick to be enabled on the server; the `wppa_upload` capability is a plugin-level privilege that site administrators may grant to lower-privileged WordPress roles via the plugin's Users settings, broadening the pool of potential attackers beyond administrators.