Summary
ZITADEL: MFA bypass via session reuse in Login V2
A vulnerability in ZITADEL’s Login V2 UI allowed a password-verified browser session to be reused for a new authentication request without re-checking a user’s enrolled second factor (TOTP, OTP, or U2F). An attacker who already knows valid credentials can fully authenticate to an application without completing MFA.
Affected Versions
Systems running one of the following versions are affected:
- 4.x:
4.0.0through4.16.0(including RC versions)
Workarounds
If an immediate upgrade is not possible, enable Force MFA (or Force MFA for local users only, if you want to exempt IdP/federated logins) in the affected organization’s, or the instance default, login policy. This makes second-factor verification mandatory for password logins and closes this session-reuse bypass.
Note that this is a broader policy change (MFA becomes mandatory for the scoped local logins) rather than a narrow fix limited to users who already self-enrolled a second factor.
Questions
If you have any questions or comments about this advisory, please email us at [email protected]
Credits
Thanks to Philippe Wechsler (@MadMonkey87) for finding and reporting the vulnerability.
Impact
ZITADEL Login V2 issues a session as soon as the user’s password is verified, before the MFA challenge is completed. If the MFA step is abandoned (for example by navigating back) and login is started again, Login V2 may reuse that existing session instead of requiring the second factor.
Session validity checks only enforced MFA verification when the organization’s login policy had Force MFA (or Force MFA for local users only) enabled. They did not treat a voluntarily enrolled second factor as required. In the common case where MFA is available on the user but not organization-mandated, a password-only session was treated as fully authenticated and used to complete the OIDC or SAML callback, bypassing the user’s second factor.
Scope note: This issue affects customer applications that authenticate users through the hosted Login V2 UI (OIDC/SAML). It does not affect Login V1. It also does not affect authentication to ZITADEL itself, including the Console, the Management/Admin APIs, and user self-management, even when Login V2 is enabled.
CVE-2026-85056 has a CVSS score of 8.2 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.80.0-v2.20.0.20260717062356-56f4798ed31f); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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The vulnerability has been addressed in the latest releases. The patch ensures Login V2 validates that any second factor enrolled on the user has been verified before an existing session can be reused to complete authentication.
- 4.x: Upgrade to $\ge$ 4.16.1
Frequently Asked Questions
- What is CVE-2026-85056? CVE-2026-85056 is a high-severity security vulnerability in github.com/zitadel/zitadel (go), affecting versions < 1.80.0-v2.20.0.20260717062356-56f4798ed31f. It is fixed in 1.80.0-v2.20.0.20260717062356-56f4798ed31f.
- How severe is CVE-2026-85056? CVE-2026-85056 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/zitadel/zitadel are affected by CVE-2026-85056? github.com/zitadel/zitadel (go) versions < 1.80.0-v2.20.0.20260717062356-56f4798ed31f is affected.
- Is there a fix for CVE-2026-85056? Yes. CVE-2026-85056 is fixed in 1.80.0-v2.20.0.20260717062356-56f4798ed31f. Upgrade to this version or later.
- Is CVE-2026-85056 exploitable, and should I be worried? Whether CVE-2026-85056 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-85056 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-85056? Upgrade
github.com/zitadel/zitadelto 1.80.0-v2.20.0.20260717062356-56f4798ed31f or later.