PWA for WP & AMP < 1.7.33 - Authenticated (Subscriber+) Arbitrary File Upload

Description

The plugin did not have a capability check in its pwaforwp_splashscreen_uploader function, and relied on CSRF check, however, the nonce was available to any authenticated user. As a result, any authenticated user (such as a subscriber) could call it and upload a malicious zip file containing a shell.