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ExploitedNot in CISA KEV yetFix available

CVE-2021-30120

Exploitation confirmed. First attested on 2021-07-06 by CISA-ADP, GCVE · kevintel.

  • Published2021-07-09
  • WeaknessCWE-669

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2021-07-06Exploitation first reportedCISA-ADP
  2. 2021-07-06SSVC exploitation set to activeCISA-ADP
  3. 2021-07-0914:15CVE publishedNVD
  4. 2026-08-1404:30Listed as exploited by GCVEGCVE

Versions per branch

NVD
Kaseya vsa
BranchAffectedFixed in
9.5≤ 9.5.6no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • GCVEexploitation2026-08-14
  • CISA-ADPSSVC decisionactive2021-07-06
  • CNACVSS 3.19.9known since 2026-10-23
  • NVDCVSS 3.17.5read 2026-10-23
  • NVDCVSS 2.05read 2026-10-23
  • NVDweakness (CWE)CWE-669read 2026-10-23
  • FIRST EPSSEPSS score5.7 %2026-11-09
  • GitHub Advisoriesadvisory—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Published
2021-07-09
Last Modified
2026-08-14
NVD status
Modified
GitHub Advisory
GHSA-r6j9-rwx4-qcj3

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.

Is CVE-2021-30120 actively exploited?

Yes. CVE-2021-30120 has been observed in active exploitation according to SSVC analysis.

What is the CVSS score for CVE-2021-30120?

CVE-2021-30120 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

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