CVE-2026-28198: Cohesity Netbackup Flex OS

High severity, CVSS 8.8. EPSS: 0.3% chance of exploitation in the next 30 days.

An authenticated, low-privileged user with access to the NetBackup Flex OS management shell could bypass the cryptographic signature verification step of a privileged support command by supplying a specially formed access credential. Successful exploitation grants the attacker an unrestricted root shell with full control over the Flex appliance host and all hosted containers, completely compromising confidentiality, integrity, and availability.

Affected products

• Cohesity Netbackup Flex OS: before 6.4 (fixed in 6.4)

Published 2026-09-18. Last modified 2026-09-18.