Proton v0.2.0 allows an attacker to create a malicious link inside a markdown file. When the victim clicks the link, the application opens the site in the current frame allowing an attacker to host JavaScript code in the malicious link in order to trigger an XSS attack. The 'nodeIntegration' configuration is set to on which allows the 'webpage' to use 'NodeJs' features, an attacker can leverage this to run OS commands.