CVE-2026-109374

ZITADEL 3.0.0 before 4.18.0 contains a missing authentication vulnerability in the hosted Login V1 UI, where the change-username handler acts on the account bound to a login flow before any factor is verified. Unauthenticated attackers can submit a victim's login name and then post a new username to rename any active human user, including administrators, locking them out.

ZITADEL before 3.4.14 and 4.x before 4.16.2 contains an authentication bypass in the hosted Login V1 UI because the 'external account not found' registration endpoint trusts client-supplied external identity fields without a completed IdP callback. Unauthenticated attackers can submit forged IDPConfigID and ExternalUserID values to pre-create an account bound to a victim's external IdP identity, which the victim's later genuine external login then signs into.

ZITADEL 3.x before 3.4.15 and 4.x before 4.17.1 contains an improper authorization vulnerability: when issuing passkey or passwordless enrollment codes, it checks only the organization in the x-zitadel-orgid header, not the target user's organization. Attackers with user-write permission in one organization can obtain an enrollment code for a user in another organization on the same instance and register their own authenticator to take over that account.

ZITADEL 3.0.0 through 3.4.15 and 4.0.0 before 4.17.3 creates links between user accounts and external identity providers without verifying a primary factor or the caller's permission, including on identify-only Login V2 sessions and via the User Service V2 AddIDPLink endpoint. An unauthenticated attacker knowing a victim's login name can bind their own external IdP identity to the victim's account and then sign in as the victim.

ZITADEL is an open-source identity infrastructure tool. Versions 4.7.0 and below are vulnerable to an unauthenticated, full-read SSRF vulnerability. The ZITADEL Login UI (V2) treats the x-zitadel-forward-host header as a trusted fallback for all deployments, including self-hosted instances. This allows an unauthenticated attacker to force the server to make HTTP requests to arbitrary domains, such as internal addresses, and read the responses, enabling data exfiltration and bypassing network-segmentation controls. This issue is fixed in version 4.7.1.

ZITADEL is an open source identity management platform. A vulnerability in the federation process allows auto-linking users from external identity providers to existing users even if the IdP is inactive or federation is disallowed. This stems from failure to enforce organization-specific security settings during authentication.

ZITADEL 3.0.0 before 4.19.2 contains an authentication bypass vulnerability in the Login V2 UI that allows unauthenticated attackers to obtain other users' session tokens by forging unsigned session cookies. Attackers can guess time-ordered session IDs around a victim's sign-in and supply them with empty tokens to receive rotated tokens, taking over accounts including MFA-completed administrator sessions.

ZITADEL 4.x before 4.19.2 and 3.x through 3.4.15 contains an authentication bypass in the SAML identity-provider intent callback. The assertion signature is verified using the provider named in the request URL, but the user is resolved from the login intent without checking they match. Attackers with organization-administrator permission can register a SAML provider with their own signing key to obtain authenticated sessions as any user linked to another SAML provider on the instance, including in other organizations.

Zitadel before version 4.16.2 contains a server-side request forgery (SSRF) vulnerability that allows attackers to make the server request internal resources through organization domain HTTP verification. The challenge fetch uses Go's default http.Get instead of the protected client, so attackers can register domains that redirect to loopback, internal, or cloud metadata addresses to scan ports and map internal networks.

ZITADEL 4.x before 4.17.1 does not check an organization's inactive state during Login V2 authentication, verifying only the individual user's status. Users of a deactivated organization who hold valid credentials, an existing session, or a refresh token can still sign in, create sessions, and obtain or refresh tokens.