External risk intelligence

NetScout nGeniusOne Code Execution and Denial of Service Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2023-26999

NetScout nGeniusOne is an enterprise network performance monitoring and service assurance platform. These systems are typically deployed as centralized management appliances or servers that often require network-wide visibility, making them common targets for placement at network edges or within management segments that are reachable by internal or external administrators.

XML External Entity Injection

Netscout Ngeniusone

6.3.4

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory details a critical vulnerability identified in NetScout nGeniusOne software, a platform used for network performance monitoring and service assurance. The flaw could permit unauthorized remote code execution and denial of service through specially crafted files, potentially impacting the integrity and availability of critical network management functions.

Code execution and service disruption risk.
Critical network management system targeted.
Confirm relevance and exposure.

Attack Path

How an attacker could exploit the issue

An attacker could send a specially crafted file to a NetScout nGeniusOne system to remotely execute arbitrary code, potentially leading to a denial of service. This attack requires no prior authentication or user interaction, as the vulnerability is exposed through the network.

Attackers can reach the system over the network.
A crafted file triggers the vulnerability.
Risk includes arbitrary code execution and denial of service.

Live Threat

Current exploitation, exposure, and threat context

The NetScout nGeniusOne system's code execution and denial-of-service vulnerabilities could allow an unauthorized remote attacker to impact the integrity and availability of network performance monitoring and service assurance functions. This could occur when a specially crafted file is uploaded to the system.

Network monitoring and assurance data could be affected.
Attacker uploads a crafted file.
Service disruption and data manipulation.

Operational Fix

Recommended remediation, mitigation, and detection steps

This critical vulnerability in NetScout nGeniusOne impacts remote code execution and denial of service. Responsibility likely falls to the platform or infrastructure team managing the nGeniusOne appliance, with support from the network and security teams for exposure assessment. The immediate priority is to identify all deployed nGeniusOne instances, confirm their network reachability and criticality, and then coordinate with the vendor or internal teams to plan remediation within a scheduled maintenance window.

Platform/infrastructure teams own this issue.
Verify network exposure and criticality.
Plan vendor-coordinated remediation.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is NetScout nGeniusOne?

NetScout nGeniusOne is an enterprise-grade platform designed for network performance monitoring and service assurance. Organizations use it as a centralized management appliance or server to gain visibility into network traffic and application health. Because it needs to monitor diverse parts of a network, it is often placed in sensitive management segments.

What does CWE-611 mean for CVE-2023-26999?

CWE-611 refers to the Improper Restriction of XML External Entity References. In the context of CVE-2023-26999, this means the software does not properly sanitize or limit how it processes specific types of data files. This weakness allows an attacker to manipulate how the system parses information, leading to unauthorized code execution or service crashes.

How is this vulnerability triggered?

An attacker triggers this issue by sending a specially crafted file to the target system over the network. The vulnerability does not require the attacker to have an existing account, nor does it require any action from a legitimate user. Simply submitting this malicious file to the nGeniusOne system is sufficient to activate the flaw.

Is my nGeniusOne deployment at risk?

Halo Surface Signal indicates this system is often placed in network segments with broad reachability to support monitoring tasks. If your nGeniusOne instance is reachable over the network—especially if it is positioned near the network edge or in segments accessible to wide internal segments—it is considered exposed to remote attackers.

What steps should I take to respond?

Begin by creating an inventory of all nGeniusOne instances in your environment to understand your total footprint. Work with your infrastructure and security teams to verify the network accessibility of each device. Finally, coordinate with your vendor representative to determine the availability of patches or configuration changes and schedule their application.

References

netscout.com/

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.