Rocket.Chat before 3.11, 3.10.5, 3.9.7, 3.8.8 is vulnerable to persistent cross-site scripting (XSS) using nested markdown tags allowing a remote attacker to inject arbitrary JavaScript in a message. This flaw leads to arbitrary file read and RCE on Rocket.Chat desktop app.
The `specializedRendering` function in Rocket.Chat server before 3.9.2 allows a cross-site scripting (XSS) vulnerability by way of the `value` parameter.
Rocket.Chat through 3.4.2 allows XSS where an attacker can send a specially crafted message to a channel or in a direct message to the client which results in remote code execution on the client side.
An XSS issue was discovered in packages/rocketchat-mentions/Mentions.js in Rocket.Chat before 0.65. The real name of a username is displayed unescaped when the user is mentioned (using the @ symbol) in a channel or private chat. Consequently, it is possible to exfiltrate the secret token of every user and also admins in the channel.
A reflected XSS issue was discovered in the registration form in Rocket.Chat before 0.66. When one creates an account, the next step will ask for a username. This field will not save HTML control characters but an error will be displayed that shows the attempted username unescaped via packages/rocketchat-ui-login/client/username/username.js in packages/rocketchat-ui-login/client/username/username.html.