---
id: CVE-2026-102893
title: Zulip is an open-source team collaboration tool
summary: >-
  Zulip is an open-source team collaboration tool. In Zulip Server versions
  through 12.1, GenericOpenIdConnectBackend matches the identity provider email
  claim to an active account's delivery_email without rejecting an explicitly
  false ema…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'
cwe:
  - CWE-287
vendor: zulip
product: zulip
affected:
  - zulip < 12.2
published: '2026-10-14'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T20:02:37.630'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-102893'
references:
  - url: >-
      https://github.com/zulip/zulip/commit/68d2d9defa39f8af96a50fc7430efc34dee120b5
    label: security-advisories@github.com
  - url: >-
      https://github.com/zulip/zulip/commit/b40f191a8c71e74fcb471f71de6a1233de157102
    label: security-advisories@github.com
  - url: 'https://github.com/zulip/zulip/pull/39913'
    label: security-advisories@github.com
  - url: 'https://github.com/zulip/zulip/releases/tag/12.2'
    label: security-advisories@github.com
  - url: 'https://github.com/zulip/zulip/security/advisories/GHSA-xw9h-9rcm-hx4m'
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
epss: 0.0039
epssPercentile: 0.32895
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-15T19:05:46.384884Z'
cvssSource: cna
ingestedAt: '2026-10-14T16:40:32.111Z'
---

## Overview

Zulip is an open-source team collaboration tool. In Zulip Server versions through 12.1, GenericOpenIdConnectBackend matches the identity provider email claim to an active account's delivery_email without rejecting an explicitly false email_verified claim. If a configured identity provider returns an email address that the authenticating user does not control together with email_verified=false, Zulip can log the user into the existing account for that address. Exploitation requires a misconfigured trusted identity provider, and deployments whose authoritative identity provider only emits email addresses controlled by the authenticating user are not affected. This issue is fixed in version 12.2.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.