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Vulnerability record · CVE-2021-30120 · published 9 July 2021

CVE-2021-30120: Kaseya vsa vulnerability

Kaseya · Vsa

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.

7.5 CVSS 3.1 High EPSS 5.7% · top 7.3% CWE-669 · CWE-669
7.5CVSS 3.1 base score, v2 5.0
5.7%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References
14 Aug 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/ PatchThird Party Advisory
https://csrit.divd.nl/CVE-2021-30120 Permissions RequiredThird Party Advisory
https://csrit.divd.nl/DIVD-2021-00011 Permissions RequiredThird Party Advisory
https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/ PatchThird Party Advisory
https://csrit.divd.nl/CVE-2021-30120 Permissions RequiredThird Party Advisory
https://csrit.divd.nl/DIVD-2021-00011 Permissions RequiredThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-30118Kaseya VSA unauthenticated arbitrary file upload leading to RCEKaseya VSA Unified RMM 9.5.4.2149 exposes /SystemTab/uploader.aspx, which accepts file uploads without validating the sessionId cookie, so any numeri…EPSS 60%analysed8.8CVE-2021-30117Kaseya VSA exportFldr.asp SQL injection via fldrIdThe /InstallTab/exportFldr.asp endpoint in Kaseya VSA is vulnerable to boolean-based blind SQL injection through the fldrId parameter. The flaw is de…EPSS 72%analysed7.5CVE-2021-30201Kaseya vsa xml external entity (xxe) vulnerabilityThe API /vsaWS/KaseyaWS.asmx can be used to submit XML to the system. When this XML is processed (external) entities are insecurely processed and fet…EPSS 25%6.7CVE-2019-14510Kaseya vsa incorrect default permissions vulnerabilityAn issue was discovered in Kaseya VSA RMM through 9.5.0.22. When using the default configuration, the LAN Cache feature creates a local account FSAdm…EPSS 0.53%6.5CVE-2021-30121Kaseya vsa inclusion from untrusted sphere vulnerabilitySemi-authenticated local file inclusion The contents of arbitrary files can be returned by the webserver Example request: `https://x.x.x.x/KLC/js/Kas…EPSS 4.8%5.4CVE-2021-30119Kaseya VSA HelpDeskTab rcResults.asp reflected XSSKaseya VSA reflects the 'result' parameter of /HelpDeskTab/rcResults.asp and the 'FileName' parameter of /done.asp back into the response without pro…EPSS 50%analysed7.8CVE-2026-31431Linux kernel algif_aead in-place crypto operation flawThe Linux kernel's algif_aead AF_ALG AEAD interface operated in-place on buffers that come from different mappings, a flaw the fix resolves by revert…KEVEPSS 3.4%analysed7.2CVE-2021-22900Pulse Connect Secure admin file upload leads to code injectionPulse Connect Secure before 9.1R11.4 allows an authenticated administrator to upload a maliciously crafted archive through the administrator web inte…KEVEPSS 14%analysed

Source: NIST National Vulnerability Database (record CVE-2021-30120), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.