A Host Header Injection issue on the Login page of Plesk Obsidian through 18.0.49 allows attackers to redirect users to malicious websites via a Host request header. NOTE: the vendor's position is "the ability to use arbitrary domain names to access the panel is an intended feature."

The feature to preview a website in Plesk Obsidian 18.0.0 through 18.0.32 on Linux is vulnerable to reflected XSS via the /plesk-site-preview/ PATH, aka PFSI-62467. The attacker could execute JavaScript code in the victim's browser by using the link to preview sites hosted on the server. Authentication is not required to exploit the vulnerability.

A GET-based XSS reflected vulnerability in Plesk Obsidian 18.0.17 allows remote unauthenticated users to inject arbitrary JavaScript, HTML, or CSS via a GET parameter.