What’s Vulnerable › Vulnerabilities

CVE-2021-43033

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 6.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-12-06 · updated 2026-06-17
• Weakness: CWE-78

Description

An issue was discovered in Kaseya Unitrends Backup Appliance before 10.5.5. Multiple functions in the bpserverd daemon were vulnerable to arbitrary remote code execution as root. The vulnerability was caused by untrusted input (received by the server) being passed to system calls.

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

Get alerted when CVE-2021-43033 or the next vulnerability affects your stack