EUVD Vulnerability Catalog

EUVD-2026-101287

Severity: CRITICAL Base Score: 9.1 CVSS Version: 4.0

Vulnerability Description

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.

CVSS Vector Analysis

Below is the complete, human-readable breakdown of the CVSS metric string: 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

▪ Attack Vector (AV): Network
▪ Attack Complexity (AC): Low
▪ Attack Requirements (AT): Present
▪ Privileges Required (PR): None
▪ User Interaction (UI): None
▪ Vulnerability Confidentiality Impact (VC): High
▪ Vulnerability Integrity Impact (VI): High
▪ Vulnerability Availability Impact (VA): None
▪ Subsequent Confidentiality Impact (SC): None
▪ Subsequent Integrity Impact (SI): None
▪ Subsequent Availability Impact (SA): None

Affected Vendors & Systems

Vendor zulip

References & Advisory Links

Metadata Profile

Database Authority

European Union Agency for Cybersecurity (ENISA) EUVD

Assigner

GitHub_M

EPSS Probability

0

Known Aliases
CVE-2026-102893
Published On

2026-10-14

Last Updated

2026-10-15