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Fencer Vulns
high 8.8

CVE-2021-43040 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-2021-29994

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5. The privileged vaultServer could be leveraged to create arbitrary writable files, leading to privilege escalation.

Patch / fix

  • kaseya unitrends_backup 10.5.5

Exploit prediction

1.83% chance of exploitation in the next 30 days, higher than 78% 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 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P

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.