ZITADEL: MFA bypass via session reuse in Login V2GHSA-9993-rfwp-rhwf
HIGHFix: zitadel/zitadel@049dbb2GHSA-9993-rfwp-rhwf is a high-severity (CVSS 8.2) Improper Authentication vulnerability in github.com/zitadel/zitadel. A fix is available for github.com/zitadel/zitadel — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-9993-rfwp-rhwf.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-9993-rfwp-rhwf by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
github.com/zitadel/zitadelReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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.
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.
Affected Versions
Systems running one of the following versions are affected:
- 4.x:
4.0.0through4.16.0(including RC versions)
Patches
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
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/zitadel/zitadel | all versions | 1.80.0-v2.20.0.20260717062356-56f4798ed31fgo get github.com/zitadel/zitadel@v1.80.0-v2.20.0.20260717062356-56f4798ed31f |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/zitadel/zitadel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/zitadel/zitadel to 1.80.0-v2.20.0.20260717062356-56f4798ed31f or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9993-rfwp-rhwf is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is GHSA-9993-rfwp-rhwf in your dependencies?
Find it across Go, including transitive dependencies.