CVE-2025-31478 Zulip Authentication Backend Configuration Bypass

High 8.2 Published 16 Apr 2025 Updated 23 Jan 2026

Attackers can create unauthorized accounts in Zulip organizations configured with SSO-only authentication and disabled email auth, bypassing access controls.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2025-31478?

CVE-2025-31478 is a high-severity authentication bypass vulnerability in zulip, published on 16 Apr 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Zulip is an open-source team collaboration tool. Zulip supports a configuration where account creation is limited solely by being able to authenticate with a single-sign on authentication backend, meaning the organization places no restrictions on email address domains or invitations being required to join, but has disabled the EmailAuthBackend that is used for email/password authentication. A bug in the Zulip server means that it is possible to create an account in such organizations, without having an account with the configured SSO authentication backend. This issue is patched in version 10.2. A workaround includes requiring invitations to join the organization prevents the vulnerability from being accessed.

Weakness: CWE-287

Which versions are affected by CVE-2025-31478?

It affects 1 product.

Products include Zulip Zulip Server.

How do I fix CVE-2025-31478?

No fix has been published for CVE-2025-31478 yet. Limit exposure of the affected software until one is available.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2025-31478 being exploited?

There is no known exploitation of CVE-2025-31478 in the wild and no public exploit code.

Sources

Also known as GHSA-qxfv-j6vg-5rqc.