CVE-2026-102893 Zulip Server - Authentication Bypass

Zulip Server <= 12.1 contains an authentication bypass caused by GenericOpenIdConnectBackend not rejecting false email_verified claims, letting attackers log into accounts with unverified emails, exploit requires misconfigured trusted identity provider.

CVSS base score 9.1 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Broken Authentication
CVSS vector
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
14 October 2026
Updated
15 October 2026
Weakness
CWE-287

Vendor fix

Upgrade to version 12.2 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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