CVE-2021-44912
In XE 1.116, when uploading the Normal button, there is no restriction on the file suffix, which leads to any file uploading to the files directory. Since .htaccess only restricts the PHP type, uploading HTML-type files leads to stored XSS vulnerabilities. If the .htaccess configuration is improper, for example before the XE 1.11.2 version, you can upload the PHP type file to GETSHELL.
Source: CVE-2021-44912