The plugin attempts to delete malicious files (such as .php) form the uploaded archive via the "Import Settings" feature, after its extraction. However, the extracted folders are not checked and it is possible to upload a zip which contained a directory with PHP file in it and then it is not removed from the disk. It is a bypass of CVE-2020-24948 which allows sending a PHP file via the "Import Settings" functionality to achieve Remote Code Execution.
WordPress Autoptimize plugin <= 2.7.7 - Arbitrary File Upload via "Import Settings" vulnerability
Autoptimize < 2.7.8 - Arbitrary File Upload via "Import Settings"