The TheGem theme for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the ajaxApi() function in all versions up to, and including, 5.10.3. This makes it possible for authenticated attackers, with Subscriber-level access and above, to update arbitrary theme options.
https://themeforest.net/item/thegem-creative-multipurpose-highperformance-wordpress-theme/16061685