Quick answers
- Is CVE-2026-102893 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-102893 being exploited in the wild.
- How severe is CVE-2026-102893?
- Informational severity, published 14 October 2026.
- Which products and versions are affected?
- Zulip Server through 12.1.
- Is there a fix for CVE-2026-102893?
- Yes: fixed in Zulip Server 12.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-102893 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-102893?
- Check whether you run Zulip Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: Zulip Server 12.2
Technical details
The GenericOpenIdConnectBackend authentication handler matches users by email address from the identity provider's email claim without validating the email_verified flag. An attacker can exploit a misconfigured identity provider that returns an email address not controlled by the authenticating user (with email_verified=false) to gain unauthorized access to the existing Zulip account associated with that email. Exploitation requires both a misconfigured trusted identity provider and the ability to control what email claims that provider returns.
Affected products
- Zulip Zulip Server through 12.1
Timeline
- 2026-10-14: advisory