XSS vulnerability - hotfix available for all affected versions

Markus Kirsch
December 18, 2020
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Learn more about the newest hotfix provided by Rocket.Chat's Security Team

Dear Rocket.Chat users,

We are providing an important security hotfix for Rocket.Chat server outside of the regular release cycle. This fix fixes a critical vulnerability that allowed Cross-Site-Scripting (XSS) in the message renderer.

We recommend you upgrade your instance as soon as possible, because the vulnerability has already become known and the creation of exploit kits by attackers is very likely.

Available versions: 3.9.3 / 3.8.4 / 3.7.4 / 2.4.14 / 1.3.5


The hotfix will only affect the message renderer. By exploiting the vulnerability, a user on the Rocket.Chat server may be able to elevate his privileges and/or modify messages, e.g. to remove traces of the exploit.

Please check our GitHub repository here (link) for your latest version. Or receive a notification whenever a new version – including hotfixes such as this one – is available by registering your server here (link).

Markus Kirsch
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