A remote code execution vulnerability in the installUpdateThemePluginAction function in index.php in WonderCMS 3.1.3, allows remote attackers to upload a custom plugin which can contain arbitrary code and obtain a webshell via the theme/plugin installer.
https://zetc0de.github.io/post/authenticated-rce-ssrf-wondercms/#authenticated-remote-code-execution
https://zetc0de.github.io/post/authenticated-rce-ssrf-wondercms/
https://packetstormsecurity.com/files/160311/WonderCMS-3.1.3-Remote-Code-Execution.html