How severe is CVE-2021-30120?

CVE-2021-30120 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-30120 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-30120?

CVE-2021-30120 affects Kaseya Vsa. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-30120?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-30120 published?

CVE-2021-30120 was published on 2021-07-09 and last updated on 2026-06-17.

CVE-2021-30120

CVE-2021-30120 is a critical-severity vulnerability in Kaseya Vsa with a CVSS 3.x base score of 9.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-669.

Key facts

Severity: Critical (CVSS 3.x base score 9.9)
CVSS v2: 5.0
EPSS exploit prediction: 6% (92nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-669
Affected product: Kaseya Vsa
Published: 2021-07-09
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-30120?: 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.
How severe is CVE-2021-30120?: CVE-2021-30120 has a CVSS 3.x base score of 9.9, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-30120 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-30120?: CVE-2021-30120 affects Kaseya Vsa. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-30120?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-30120 published?: CVE-2021-30120 was published on 2021-07-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:kaseya:vsa:*:*:*:*:-:*:*:*

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CVE-2021-30118 — Critical (CVSS 9.8): An attacker can upload files with the privilege of the Web Server process for Kaseya VSA Unified Remote Monitoring &…
CVE-2021-30117 — Critical (CVSS 9.8): The API call /InstallTab/exportFldr.asp is vulnerable to a semi-authenticated boolean-based blind SQL injection in the…
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CVE-2021-30119 — Medium (CVSS 5.4): Authenticated reflective XSS in HelpDeskTab/rcResults.asp The parameter result of /HelpDeskTab/rcResults.asp is…

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