Privilege Escalation via Cryptographic Signature Verification Bypass in NetBackup Flex OS Shell (CVE-2026-28198) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-28198

Privilege Escalation via Cryptographic Signature Verification Bypass in NetBackup Flex OS Shell

Answer in brief

CVE-2026-28198 records a Unknown severity vulnerability in Privilege Escalation via Cryptographic Signature Verification Bypass in NetBackup Flex OS Shell. The current sources do not mark it as known exploited. The current feed maps Cohesity/NetBackup Flex OS (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 18, 2026Updated Sep 18, 2026Source checked Sep 18, 2026First seen by HOL Sep 18, 2026Material review Sep 18, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Cohesity/NetBackup Flex OS (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Cohesity/NetBackup Flex OSgeneric	>=0 <6.4	6.4

Recommended response

Check inventory. Check lockfiles and deployed manifests for Cohesity/NetBackup Flex OS.
Review the reported fix. Update Cohesity/NetBackup Flex OS to 6.4 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 18, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 18, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 18, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.