CVE-2021-30120Known exploitationNetwork attack vector

Two-factor authentication bypass via client-controlled enforcement flag

Published Jul 9, 2021 · Updated Aug 14, 2026

Authentication bypass in Kaseya VSA before 9.5.7 allows remote authenticated users to skip two-factor authentication. The login response exposes MFARequired and MFAEnroled booleans to the client, and the server trusts a changed MFARequered value instead of enforcing MFA itself. Possession of a valid username and password plus interception of the login exchange is sufficient to complete sign-in without the second factor.

CVSS severity7.5
High
EPSS probability5.70%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Kaseya VSA before 9.5.7 allows remote authenticated users to skip two-factor authentication. The login response exposes MFARequired and MFAEnroled booleans to the client, and the server trusts a changed MFARequered value instead of enforcing MFA itself. Possession of a valid username and password plus interception of the login exchange is sufficient to complete sign-in without the second factor.

The record

CVE
CVE-2021-30120
Published
Jul 9, 2021
Updated
Aug 14, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-669, T1556.006
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.9MITRECVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-669Incorrect Resource Transfer Between Spheres
T1556.006Multi-Factor Authentication

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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