CVE-2021-301120: Kaseya 2FA Bypass Vulnerability Exploitation (CVE-2021-30120)
The short version: Kaseya VSA before 9.5.7 allows attackers to bypass the 2FA requirement. 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. BreachRisk discovers exposed instances from your attack surface and flags this finding so you can prioritize by real-world breach risk.
At a glance
| Fact | Detail |
|---|---|
| Our severity take | High — BreachRisk score 6.0 (impact 3, likelihood 4) |
| CVSS v3.1 (NVD) | Unknown at time of writing |
| In CISA KEV? | Unknown at time of writing — check the KEV catalog |
| Known exploited? | Unknown at time of writing |
| Requires authenticated session? | Unknown at time of writing |
| CVE | CVE-2021-301120, CVE-2021-30120 |
What you need to know
Exposed Kaseya VSA Server appears vulnerable to exploitation of 2FA bypass vulnerability (CVE-2021-30120).
- How they find it — internet-facing exposure of the affected product is discoverable by routine scanning.
- How they use it — attackers exploit the vulnerability against reachable instances.
- What it leads to — compromise of the affected service and, depending on placement, a foothold for further movement.
How serious we see it
High — based on BreachRisk impact and likelihood scoring for this threat definition (score 6.0/9). Treat internet-facing instances as priority; confirm exposure and patch status before assuming you're clear.
Recommendations
- Apply latest security update to exposed Kaseya VSA Server, all versions prior to 9.5.7 with MFA in use are vulnerable.
- If update cannot be immediately completed, inform employees with MFA in use of potential threat.
How BreachRisk sees it
BreachRisk discovers internet-facing assets tied to this threat, fingerprints the product where possible, and flags exposure for CVE-2021-301120. Where authorized, it can go beyond detection with a bounded, non-disruptive check rather than leaving you with a maybe. Continuous outside-in coverage means the exposed service is already on your radar ranked by how it actually gets used against you.