ZITADEL: MFA bypass via session reuse in Login V2

[ Description ]Official description

ZITADEL is an open source identity management platform. From 4.0.0 until 4.16.1, ZITADEL Login V2 creates a browser session after password verification and can reuse that session for a later authentication request without verifying a user's enrolled TOTP, OTP, or U2F second factor. When the MFA step is abandoned and login starts again, session-validity checks require MFA only when the organization enables Force MFA or Force MFA for local users only, so a voluntarily enrolled factor can be skipped while completing an OIDC or SAML callback for a customer application. Login V1, the ZITADEL Console, Management and Admin APIs, and user self-management are not affected. This issue is fixed in version 4.16.1.

[ Fixes ]Fixes and patches

• github.com/zitadel/zitadel 1.80.0-v2.20.0.20260717062356-56f4798ed31fFixed version · GitHub Advisories · go package github.com/zitadel/zitadel: upgrade to 1.80.0-v2.20.0.20260717062356-56f4798ed31f or later (affected < 1.80.0-v2.20.0.20260717062356-56f4798ed31f)

[ Packages ]Affected open-source packages

• github.com/zitadel/zitadel goAffected < 1.80.0-v2.20.0.20260717062356-56f4798ed31f · fixed in 1.80.0-v2.20.0.20260717062356-56f4798ed31f · GHSA-9993-rfwp-rhwf

[ References ]References

• github.com/zitadel/zitadel/commit/049dbb25a56587fb3980c85c99819cad69f637db
• github.com/zitadel/zitadel/commit/56f4798ed31fc1cfcd9a0e7f6f0152289d2fdc43
• github.com/zitadel/zitadel/releases/tag/v4.16.1
• github.com/zitadel/zitadel/security/advisories/GHSA-9993-rfwp-rhwf