Vulnerability · Published Oct 14, 2026 · Assigned by GitHub_M

CVE-2026-102893Zulip: OpenID Connect authentication ignores the email_verified claim

Critical 9.1

In plain English

A critical-severity improper authentication in zulip from zulip. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities).

Severity (CVSS 4.0)9.1Critical

Exploit odds (30 days)0.4%top 66.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
zulip	zulip	< 12.2

Weakness: CWE-287 · 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

References

https://github.com/zulip/zulip/security/advisories/GHSA-xw9h-9rcm-hx4m x_refsource_CONFIRM
https://github.com/zulip/zulip/pull/39913 x_refsource_MISC
https://github.com/zulip/zulip/commit/68d2d9defa39f8af96a50fc7430efc34dee120b5 x_refsource_MISC
https://github.com/zulip/zulip/commit/b40f191a8c71e74fcb471f71de6a1233de157102 x_refsource_MISC
https://github.com/zulip/zulip/releases/tag/12.2 x_refsource_MISC