The Advance Guest Post WordPress plugin through 1.9 does not properly restrict or validate file...

The Advance Guest Post WordPress plugin through 1.9 does not properly restrict or validate file uploads, authorizing an upload action with a nonce exposed to every front-end visitor and checking only a file's leading bytes, allowing unauthenticated users to upload arbitrary PHP files and execute code remotely.

Successful exploitation additionally requires the target to run PHP 7.x; on PHP 8.0 and later the vulnerable code path raises a fatal error before the file is written.