Zulip Server Cross-Site Scripting Vulnerability in Digest Preview

A cross-site scripting (XSS) vulnerability has been identified in Zulip Server versions 2.0.0-rc1 prior to 10.4. The issue arises in the '/digest/' URL, which previews the content of the weekly email digest. This preview, while not the actual digest, is vulnerable to XSS attacks through topic and channel names. The vulnerability requires user interaction and can be exploited by accessing the digest preview URL.

Impact

Exploitation of this vulnerability allows for cross-site scripting, where an attacker can inject malicious scripts that are executed in the context of the user's browser.

Remediation

Users can upgrade to Zulip Server 10.4 or deny access to the '/digest/' URL, which is unused in most installations.