The WooCommerce Help Scout WordPress plugin before 2.9.1 (https://woocommerce.com/products/woocommerce-help-scout/) allows unauthenticated users to upload any files to the site which by default will end up in wp-content/uploads/hstmp.
https://github.com/EmmanuelCruzL/CVE_2021_24212
https://wpscan.com/vulnerability/cf9305e8-f5bc-45c3-82db-0ef00fd46129
https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-11126
http://dzv365zjfbd8v.cloudfront.net/changelogs/woocommerce-help-scout/changelog.txt