What’s Vulnerable › Vulnerabilities

CVE-2021-43042

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.0% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-12-06 · updated 2026-06-17
• Weakness: CWE-120

Description

An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5. A buffer overflow existed in the vaultServer component. This was exploitable by a remote unauthenticated attacker.

Affected products

• Kaseya Unitrends Backup: from 10.0 before 10.5.5 — fixed in 10.5.5

How to fix

Upgrade to a fixed version: Kaseya Unitrends Backup 10.5.5. Check the vendor advisory for mitigations.

References

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

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