The wp_ajax_upload-remote-file AJAX action of the External Media WordPress plugin before 1.0.34 was vulnerable to arbitrary file uploads via any authenticated users.
https://www.wordfence.com/blog/2021/05/critical-vulnerability-patched-in-external-media-plugin/
https://wpscan.com/vulnerability/4fb90999-6f91-4200-a0cc-bfe9b34a5de9