HOMEVULNERABILITIESCVE-2021-43037
HIGH

CVE-2021-43037

CWE-427Published: December 6, 2021· Updated: Jun 17, 2026

7.8
CVSS v3.1

Official Description

An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5. The Unitrends Windows agent was vulnerable to DLL injection and binary planting due to insecure default permissions. This allowed privilege escalation from an unprivileged user to SYSTEM.

NVD Source

Technical Analysis

CVE-2021-43037 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 7.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Vendors & Products

kaseya1 product(s)
unitrends backup
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://helpdesk.kaseya.com/hc/en-gb/articles/4412762258961
ADVISORYhttps://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-1
ADVISORYhttps://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-2
ADVISORYhttps://helpdesk.kaseya.com/hc/en-gb/articles/4412762258961
ADVISORYhttps://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-1
ADVISORYhttps://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-2

All References (6)

→
https://helpdesk.kaseya.com/hc/en-gb/articles/4412762258961Vendor Advisory
→
https://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-1Exploit · Third Party Advisory
→
https://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-2Exploit · Third Party Advisory
→
https://helpdesk.kaseya.com/hc/en-gb/articles/4412762258961Vendor Advisory
→
https://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-1Exploit · Third Party Advisory
→
https://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-2Exploit · Third Party Advisory

Quick Facts

CVE IDCVE-2021-43037
CVSS Score7.8 / 10
SeverityHIGH
WeaknessCWE-427
CISA KEVNo
Affected1 vendor(s)
PublishedDec 6, 2021

Related CVEs (CWE-427)

CVE-2025-4981
9.9
CVE-2023-31543
9.8
CVE-2019-7653
9.8
CVE-2018-12805
9.8
CVE-2019-9546
9.8
CVE-2023-41117
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-43037 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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