Hey Skyliner, I have found Email Spoofing type of Vulnerability in your Website. Attacker can use your E-Mail to send emails to others.
Email spoofing is the creation of email messages with a forged sender address. Because the core email protocols do not have any mechanism for authentication, it is common for spam and phishing emails to use such spoofing to mislead the recipient about the origin of the message
Not Only firstname.lastname@example.org involved in it, All the Emails develop in https://www.skyliner.io/ may be affect by it...
Steps to Produce this Issue: 1) Goto: https://emkei.cz/ 2) Add email@example.com "From Email" in https://emkei.cz/ 3) Click Send Button, 4) The Email from firstname.lastname@example.org will be send to the Email you enter.
Another way, <?php $to = "email@example.com"; $subject = "Email Spoofing Test"; $txt = "This is Email Spoofing"; $headers = "From: firstname.lastname@example.org"; mail($to,$subject,$txt,$headers); ?>
Save this code in PHP file, & upload it on online server, Execute it & you can see The email will be send to your Desired Email
See Screenshots below, I received Email from your website.
Fix: Improve Your Mailer, Turn on some more Security filters. Read More about Email Spoofing here: http://searchsecurity.techtarget.com/definition/email-spoofing
Thanks! I hope you will fix this issue soon as possible, And i know this is not eligible for any bounty but i am expecting atleast a THANKS or SWAG maybe :)