CVE-2021-30120

CriticalCVSS 9.9

Published: 09/07/2021(UTC)Updated: 14/08/2026(UTC)Translated: 14/08/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Very high risk

5.70%

92th percentile - higher than 92% of all known CVEs

Summary

Kaseya VSA before 9.5.7 allows attackers to bypass the 2FA requirement. The 2FA check is enforced client-side instead of server-side and can be bypassed using a local proxy.

Risk Assessment

Bypassing 2FA renders the mechanism useless, increasing the risk of unauthorized access to user accounts and the VSA system.

Recommendation

Upgrade Kaseya VSA to 9.5.7 or later. Ensure 2FA verification is enforced server-side.

Original NVD description (English source)

Kaseya VSA before 9.5.7 allows attackers to bypass the 2FA requirement. The need to use 2FA for authentication in enforce client-side instead of server-side and can be bypassed using a local proxy. Thus rendering 2FA useless. Detailed description --- During the login process, after the user authenticates with username and password, the server sends a response to the client with the booleans MFARequired and MFAEnroled. If the attacker has obtained a password of a user and used an intercepting proxy (e.g. Burp Suite) to change the value of MFARequered from True to False, there is no prompt for the second factor, but the user is still logged in.