CVE-2021-40386: Kaseya Unitrends Client/Agent through 10.5,5 allows remote attackers to execute arbitrary code.

Q: How do I fix CVE-2021-40386?

unitrends backup: upgrade to newer than 10.5.5. Exact commands for each OS are on this page.

Q: Is CVE-2021-40386 being exploited?

CVE-2021-40386 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-40386 affect?

CVE-2021-40386 affects unitrends backup. Severity is critical (CVSS 9.8). Kaseya Unitrends Client/Agent through 10.5,5 allows remote attackers to execute arbitrary code.

Q: How urgent is CVE-2021-40386?

Priority 59/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-40386 is a critical-severity flaw (CVSS 9.8) affecting unitrends backup. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Kaseya Unitrends Client/Agent through 10.5,5 allows remote attackers to execute arbitrary code.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.9% (top 20%)
CISA exploited list	No
Published	2022-04-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: kaseya

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-04-15 05:15 UTCPublished CVE record published
2026-06-17 04:06 UTCUpdated Record last modified

kaseya unitrends backup UPGRADE

Affected: <= 10.5.5

Fixed in: newer than 10.5.5

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy unitrends-backup || rpm -q unitrends-backup || unitrends-backup --version

2. UPGRADE to newer than 10.5.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade unitrends-backup

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade unitrends-backup

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-40386?

unitrends backup: upgrade to newer than 10.5.5. Exact commands for each OS are on this page.

Is CVE-2021-40386 being exploited?

CVE-2021-40386 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-40386 affect?

CVE-2021-40386 affects unitrends backup. Severity is critical (CVSS 9.8). Kaseya Unitrends Client/Agent through 10.5,5 allows remote attackers to execute arbitrary code.

How urgent is CVE-2021-40386?

Priority 59/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-43044 CRITICAL 9.8 UPGRADE An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5
CVE-2021-43043 MEDIUM 6.5 UPGRADE An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5
CVE-2021-43042 CRITICAL 9.8 UPGRADE An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5
CVE-2021-43041 HIGH 8.8 UPGRADE An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5
CVE-2021-43040 HIGH 8.8 UPGRADE An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5

References

← Back to latest CVEs