vBulletin 5.x through 5.5.4 allows remote command execution via the widgetConfig[code] parameter in an ajax/render/widget_php routestring request.
https://github.com/ludy-dev/vBulletin_Routestring-RCE
https://github.com/psychoxploit/vbull
https://github.com/FarjaalAhmad/CVE-2019-16759
https://github.com/theLSA/vbulletin5-rce
https://github.com/r00tpgp/http-vuln-CVE-2019-16759
https://github.com/M0sterHxck/CVE-2019-16759-Vbulletin-rce-exploit
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-16759
https://seclists.org/fulldisclosure/2019/Sep/31
http://seclists.org/fulldisclosure/2020/Aug/5
http://packetstormsecurity.com/files/158866/vBulletin-5.x-Remote-Code-Execution.html
http://packetstormsecurity.com/files/158830/vBulletin-5.x-Remote-Code-Execution.html
http://packetstormsecurity.com/files/158829/vBulletin-5.x-Remote-Code-Execution.html
http://packetstormsecurity.com/files/155633/vBulletin-5.5.4-Remote-Command-Execution.html
http://packetstormsecurity.com/files/154648/vBulletin-5.x-Pre-Auth-Remote-Code-Execution.html