Thank you Igor,
I don't want to replace the whole ruleset but just add one rule:
SecRule REQUEST_HEADERS "JDatabaseDriverMysqli" "phase:1,id:'999000',deny,t:urlDecode,t:removeNulls,status:403,log,noauditlog,msg:'Joomla RCE CVE-2015-8562'"
Thanks,
Erwin