CVE-2025-64103: Zitadel Bypass Second Authentication Factor
Summary
A vulnerability in Zitadel's token verification prematurely marked sessions as authenticated when only one factor was verified.
Impact
Zitadel provides an API for managing sessions, enabling custom login experiences in a dedicated UI or direct integration into applications. Session Tokens are issued for active sessions, which can be used as Bearer tokens to call the Zitadel API.
Starting from 2.55.0 (see other affected versions below), Zitadel only required multi factor authentication in case the login policy has either enabled requireMFA or requireMFAForLocalUsers. If a user has set up MFA without this requirement, Zitadel would consider single factor auhtenticated sessions as valid as well and not require multiple factors.
Bypassing second authentication factors weakens multifactor authentication and enables attackers to bypass the more secure factor. An attacker can target the TOTP code alone, only six digits, bypassing password verification entirely and potentially compromising accounts with 2FA enabled.
Affected Versions
Systems using the session API (v2 beta and v2) directly or via the new login UI in the following versions are affected: - 4.x: 4.0.0 to 4.5.0 (including RC versions) - 3.x: 3.0.0 to 3.4.2 (including RC versions) - 2.x: v2.53.6 to v2.53.9, v2.54.3 to v2.54.10, 2.55.0 to 2.71.17
Patches
The vulnerability has been addressed in the latest releases. The patch resolves the issue by requiring a configured second factor regardless of the login policies requireMFA or requireMFAForLocalUsers configuration.
4.x: Upgrade to >=4.6.0 3.x: Update to >=3.4.3 2.x: Update to >=2.71.18
Workarounds
The recommended solution is to update Zitadel to a patched version.
Questions
If you have any questions or comments about this advisory, please email us at security@zitadel.com
Credits
This vulnerability was found by zentrust partners GmbH during a scheduled penetration test. Thank you to the analysts Martin Tschirsich, Joud Zakharia, Christopher Baumann. The full report will be made public after the complete review.
Other sources
Starting from 2.53.6, 2.54.3, and 2.55.0, Zitadel only required multi factor authentication in case the login policy has either enabled requireMFA or requireMFAForLocalUsers. If a user has set up MFA without this requirement, Zitadel would consider single factor auhtenticated sessions as valid as well and not require multiple factors. Bypassing second authentication factors weakens multifactor authentication and enables attackers to bypass the more secure factor. An attacker can target the TOTP code alone, only six digits, bypassing password verification entirely and potentially compromising accounts with 2FA enabled. This vulnerability is fixed in 4.6.0, 3.4.3, and 2.71.18.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2025-64103?
The severity of CVE-2025-64103 is considered to be high due to the risk of unauthorized access without multi-factor authentication.
How do I fix CVE-2025-64103?
To fix CVE-2025-64103, ensure that the login policy has 'requireMFA' or 'requireMFAForLocalUsers' enabled in your Zitadel configuration.
Which versions of Zitadel are affected by CVE-2025-64103?
CVE-2025-64103 affects Zitadel versions from 2.53.6 to 2.55.0, as well as versions up to 4.6.0, 3.4.3, and 2.71.18.
What are the implications of not addressing CVE-2025-64103?
Not addressing CVE-2025-64103 could lead to unauthorized access to user accounts as single-factor authentication may be accepted without MFA requirements.
Is multi-factor authentication necessary with CVE-2025-64103?
With CVE-2025-64103, multi-factor authentication is necessary only if the login policy explicitly requires it, which may leave some users vulnerable.