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Fencer Vulns
high 7.8

CVE-2021-43037 json

An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5.

published 2021-12-06 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-29991

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

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.

Patch / fix

  • kaseya unitrends_backup 10.5.5

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • cyberonesecurity.com https://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-1 referenced PoC, tagged "exploit" by a source, unverified
  • cyberonesecurity.com https://www.cyberonesecurity.com/blog/exploiting-kaseya-unitrends-backup-appliance-part-2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.9 AV:L/AC:M/Au:N/C:C/I:C/A:C

Classification

Weakness
  • CWE-427 Uncontrolled Search Path Element

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.