CVE-2024-56136: Zulip Server

Medium severity, CVSS 5.3. EPSS: 0.6% chance of exploitation in the next 30 days.

Zulip server provides an open-source team chat that helps teams stay productive and focused. Zulip Server 7.0 and above are vulnerable to an information disclose attack, where, if a Zulip server is hosting multiple organizations, an unauthenticated user can make a request and determine if an email address is in use by a user. Zulip Server 9.4 resolves the issue, as does the `main` branch of Zulip Server. Users are advised to upgrade. There are no known workarounds for this issue.

Affected products

• Zulip Zulip Server: from 7.0, before 9.4 (fixed in 9.4)

Published 2025-01-16. Last modified 2026-06-17.