CVE-2026-105209

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.

ZITADEL 3.x before 3.4.14 and 4.x before 4.16.2 contains an authentication bypass in the hosted Login V1 and Login V2 UIs that accepts passkey or other authenticator enrollment on identify-only login sessions, before any primary factor is verified. Unauthenticated attackers knowing only a victim's login name can register an attacker-controlled authenticator and log in as that user, bypassing existing passwords and MFA.

ZITADEL before 4.17.1 contains an authentication bypass vulnerability in Login V2 that allows unauthenticated attackers to take over accounts by obtaining OTP codes via the returnCode delivery type. Attackers knowing a login name of a victim with OTP-Email and OTP-SMS enrolled can read both codes from server-action responses to gain MFA-authenticated sessions, including administrator takeover.

ZITADEL 3.x before 3.4.15 and 4.x before 4.17.1 contains a missing authentication flaw in the hosted Login V1 UI, whose second-factor enrollment and initialization handlers act on an identify-only session before any primary factor is verified. Attackers knowing only a victim's login name can enroll attacker-controlled TOTP, OTP-SMS, OTP-Email, or U2F factors, overwrite the verified phone number, and enumerate users through discrepant errors.

ZITADEL 4.x before 4.17.3 and 3.x through 3.4.15 protects IdP intent tokens with unauthenticated, malleable encryption, allowing authenticated users to tamper with their own token so it is accepted for another user's external login intent. An attacker who predicts a victim's in-flight intent identifier and wins a timing race can call /v2/idp_intents or /v2/sessions to steal the victim's IdP tokens or hijack their session.

ZITADEL 3.0.0 through 3.4.15 and 4.x before 4.17.3 contains an incorrect authorization flaw in the User Service API, which verifies user.read against the caller's organization rather than the organization owning the target user. An authenticated member holding org-scoped user.read can query GET /v2/users/{userId}/authentication_methods to learn which authentication method types users in other organizations have registered.

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 3.0.0 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.