Update Your Mailcow Installation – Critical XSS Vulnerability Patched

CVSScvssV3_1: 8.3

Mailcow is an open source email and collaboration platform that many organizations rely on. Unfortunately, a serious vulnerability was recently discovered that could allow hackers to compromise administrator accounts.

The vulnerability is a cross-site scripting (XSS) flaw that is present in the quarantine interface. XSS bugs occur when untrusted data is displayed on a website without being sanitized, allowing attackers to sneak malicious JavaScript code into otherwise legitimate pages.

In Mailcow, a hacker could craft a specially malformed email and send it to the server. If an administrator then viewed the quarantined message, the hidden JavaScript payload would execute in their browser whenever they accessed the quarantine page. This could potentially reveal sensitive information like login cookies.

The good news is that Mailcow developers have already addressed this issue with the latest version update. It is critical that all Mailcow installations are updated immediately to version 2023-11 or later to apply the security fix.

To protect yourself, be sure to always keep your Mailcow software up to date. Also use strong and unique administrator passwords. And be cautious when interacting with untrusted emails, even if they appear to be in your quarantine. Staying on top of patches is the best way to defend against vulnerabilities like this XSS flaw.