CVE-2026-28198 Privilege Escalation via Cryptographic Signature Verification Bypass in NetBackup Flex OS Shell
Authenticated low-privileged users can bypass signature verification to gain root access on NetBackup Flex OS appliances.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-28198?
CVE-2026-28198 is a critical vulnerability in Cohesity NetBackup Flex OS, published on 18 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-347
Which versions are affected by CVE-2026-28198?
How do I fix CVE-2026-28198?
No fix has been published for CVE-2026-28198 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-28198 being exploited?
There is no known exploitation of CVE-2026-28198 in the wild and no public exploit code.
Sources
Also known as GHSA-h4hc-x5f6-wfc4.