CVE-2021-40386
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedKaseya Unitrends Client/Agent through 10.5,5 allows remote attackers to execute arbitrary code.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceKaseya Unitrends Client/Agent through version 10.5.5 contains a vulnerability that allows remote attackers to execute arbitrary code. The specific attack vector and vulnerability type are not detailed in the available description, but the critical CVSS score of 9.8 indicates a pre-authentication network-exploitable flaw with complete system compromise potential.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 10.5.5CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Identify Kaseya Unitrends installationOn Windows, check Add/Remove Programs or the program directory (typically C:\Program Files\Unitrends or C:\Program Files\Kaseya). On Linux, check /opt/Unitrends or run 'rpm -qa | grep -i unitrends' or 'dpkg -l | grep -i unitrends'.Affected if Kaseya Unitrends Backup or Client/Agent is installed on the system
-
Determine installed versionOn Windows, right-click the Unitrends application in Add/Remove Programs to view the version, or check the version property of the executable in the installation directory. On Linux, run 'rpm -qa | grep -i unitrends' or check /opt/Unitrends/version 2>/dev/null.Affected if The installed version is 10.5.5 or any version lower than 10.5.5
-
Verify network exposureCheck if the Unitrends service is listening on network ports. Run 'netstat -an | findstr LISTENING' on Windows or 'netstat -tlnp | grep -i unitrends' on Linux to identify listening ports. Review firewall rules to confirm the service is accessible from untrusted networks.Affected if The Unitrends service is exposed to untrusted network segments or the internet on any port
-
Check for unauthorized access indicatorsReview system logs for unusual authentication attempts, new user accounts, or unexpected process executions. Check Unitrends application logs in the installation directory for suspicious activity around the backup agent service.Affected if Any signs of unauthorized access, unusual processes, or unexpected modifications to the backup agent configuration
The environment is affected if Kaseya Unitrends Backup or Client/Agent version 10.5.5 or lower is installed and is network-accessible, particularly from untrusted networks.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade Kaseya Unitrends Client/Agent to a version beyond 10.5.5 that contains the security patch. If immediate patching is not possible, restrict network access to the affected systems and monitor for indicators of compromise.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40386 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-40386 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data