CVE-2021-40387

Name: CVE-2021-40387
Creator: NVD / NIST
Published: 2021-09-01T21:15:07.393+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 2.43%

Last modified Jun 17, 2026

CVE-2021-40387 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. An issue was discovered in the server software in Kaseya Unitrends Backup Software before 10.5.5-2. There is authenticated remote code execution.. EPSS estimates a 2.43% chance of exploitation in the next 30 days.

Description

An issue was discovered in the server software in Kaseya Unitrends Backup Software before 10.5.5-2. There is authenticated remote code execution.

Metrics

CVSS 3.1

8.8/10

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

EPSS Probability

2.43%

82.1th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Kaseya	Unitrends Backup Software	< 10.5.5-2

References

https://csirt.divd.nl/csirt-divd-nl/cases/DIVD-2021-00014/Third Party Advisory
https://csirt.divd.nl/csirt-divd-nl/cases/DIVD-2021-00014/Third Party Advisory

Timeline

Published: Sep 1, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-40387?

An issue was discovered in the server software in Kaseya Unitrends Backup Software before 10.5.5-2. There is authenticated remote code execution.

How severe is CVE-2021-40387?

CVE-2021-40387 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 2.43% probability of exploitation in the next 30 days.

How do I fix CVE-2021-40387?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-40387?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST