Privilege Escalation via Cryptographic Signature Verification Bypass in NetBackup Flex OS Shell
Summary
| CVE | CVE-2026-28198 |
|---|---|
| State | PUBLISHED |
| Assigner | ENISA |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-18 12:17:24 UTC |
| Updated | 2026-09-18 19:24:36 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 9.4 CRITICAL from a6d3dc9e-0591-4a13-bce7-0f5b31ff6158
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.001990000 probability, percentile 0.099770000 (date 2026-09-21)
Problem Types: CWE-347 | CWE-347 CWE-347 Improper verification of cryptographic signature
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | a6d3dc9e-0591-4a13-bce7-0f5b31ff6158 | Secondary | 9.4 | CRITICAL | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/C... |
| 4.0 | CNA | CVSS | 9.4 | CRITICAL | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
| 3.1 | a6d3dc9e-0591-4a13-bce7-0f5b31ff6158 | Secondary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Cohesity | NetBackup Flex OS | affected 6.4 custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| www.cvcn.gov.it/cvcn/cve/CVE-2026-28198 | a6d3dc9e-0591-4a13-bce7-0f5b31ff6158 | www.cvcn.gov.it | |
| github.com/cohesity/SecAdvisory/blob/master/COH-2026-0001.md | a6d3dc9e-0591-4a13-bce7-0f5b31ff6158 | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Additional Advisory Data
Workarounds
CNA: Restrict management shell access to authorized administrators only. No compensating control fully eliminates the risk; upgrading is required.