# CVE-2026-102893: Zulip Server OpenID Connect email verification bypass

Source: https://junglewise.ai/threats/cve-2026-102893-zulip-is-an-open-source-team-collaboration-tool-in-zulip-server  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-14. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-102893 · Severity: info · Published 2026-10-14

Zulip Server is a team collaboration platform that uses OpenID Connect for single sign-on authentication. An attacker with control of a misconfigured identity provider can log into accounts of other users if that identity provider returns unverified email addresses. This allows account takeover without the target user's credentials or knowledge, provided the organization's identity provider is not properly configured to only emit email addresses controlled by the authenticating user.

Technologies: [Zulip Server](https://junglewise.ai/threats/technologies/zulip-server). Vendors: [Zulip](https://junglewise.ai/threats/vendors/zulip).

## 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

## References

- [https://github.com/zulip/zulip/commit/68d2d9defa39f8af96a50fc7430efc34dee120b5](https://github.com/zulip/zulip/commit/68d2d9defa39f8af96a50fc7430efc34dee120b5)
- [https://github.com/zulip/zulip/commit/b40f191a8c71e74fcb471f71de6a1233de157102](https://github.com/zulip/zulip/commit/b40f191a8c71e74fcb471f71de6a1233de157102)

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