Home-Gallery.org is a self-hosted open-source web gallery to browse personal photos and videos. In 1.15.0 and earlier, the default setup of home-gallery is vulnerable to DNS rebinding. Home-gallery is set up without TLS and user authentication by default, leaving it vulnerable to DNS rebinding. In this attack, an attacker will ask a user to visit their website. The attacker website will then change the DNS records of their domain from their IP address to the internal IP address of the home-gallery instance. To tell which IP addresses are valid, we can rebind a subdomain to each IP address we want to check, and see if there is a response. Once potential candidates have been found, the attacker can launch the attack by reading the response of the web server after the IP address has changed. When the attacker domain is fetched, the response will be from the home-gallery instance, not the attacker website, because the IP address has been changed. Due to a lack of authentication, home-gallery photos can then be extracted by the attacker website.
The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.