External risk intelligence

Oracle Net Services Remote Access and Denial of Service Vulnerability.

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-47040

This vulnerability affects Oracle Net Services, which is typically deployed behind firewalls or internal network segments to facilitate database connectivity. While the protocol is network-accessible, it is not standard practice to expose Oracle Database network listeners directly to the public internet, making public exposure uncommon in typical real-world deployments.

Missing Authentication

Oracle Database Server

19.3 to 19.3121.3 to 21.2223.4 to 23.26.2

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in Oracle Database's Net Services component could allow an unauthenticated attacker to gain unauthorized access to critical data or cause service disruptions. The issue is rated as critical due to its potential impact on confidentiality and availability.

Unauthenticated access to critical data.
Could disrupt essential database services.
Confirm relevance and check for exposure.

Attack Path

How an attacker could exploit the issue

An unauthenticated attacker with network access can target Oracle Net Services. This vulnerability in Oracle Database Server's Net Services component can lead to unauthorized access to sensitive data or a denial-of-service condition.

Network access required.
Attacker triggers via Oracle Net.
Risk of data access or crash.

Live Threat

Current exploitation, exposure, and threat context

An unauthenticated attacker with network access could exploit an easily exploitable vulnerability in Oracle Net Services, potentially leading to unauthorized access to critical data or complete denial of service. This could impact the confidentiality and availability of data managed by Oracle Net Services when supported by the advisory.

Critical data could be accessed.
Attacker gains unauthorized access to data.
Services could crash or frequently repeat crashes.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Oracle Database Server's Net Services component is affected by this vulnerability, potentially impacting application owners and infrastructure teams responsible for database systems. The first practical step is to identify all instances of the affected Oracle Database versions within your environment. Subsequently, confirm the business criticality of these instances and determine their network reachability to prioritize remediation efforts.

Identify accountable database owners.
Verify network exposure and criticality.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is Oracle Net Services in this context?

Oracle Net Services is the communication software layer within an Oracle Database Server. It acts as the networking bridge that allows client applications, such as business tools or web servers, to connect to the database and exchange data. By managing these connections, it ensures that requests from various parts of an organization reach the database engine reliably.

What kind of vulnerability is CVE-2026-47040?

This is a network-based vulnerability that allows an unauthenticated attacker to interact directly with the database's communication layer. Because it does not require a password or user account, it essentially provides a bypass for standard authentication. This weakness can lead to two main outcomes: the unauthorized exposure of sensitive information stored in the database or a forced crash that stops the service from functioning entirely.

How can an attacker trigger this vulnerability?

An attacker triggers the vulnerability by sending malicious, specifically crafted network traffic directly to the Oracle Net listener. Crucially, this bug requires active network reachability to the Oracle Net service; it cannot be triggered through local file manipulation or by a user who lacks direct network access to the database port. If the database listener is blocked by a firewall, an attacker on the outside cannot reach the component to initiate the attack.

Is my database at risk if it is internal?

According to Halo Surface Signal, this vulnerability is classified as external because the protocol relies on network access, but it is uncommon for these listeners to be directly exposed to the public internet. If your database is kept behind internal firewalls or restricted network segments, the risk is reduced. However, you should still care if any device on your internal network can communicate with the database, as that lateral access could be used to exploit the flaw.

What should I do first to address this?

Start by performing an inventory of your environment to identify all servers running the specific Oracle Database versions listed in the advisory. Once identified, evaluate the network placement of these assets to confirm which ones are reachable from untrusted zones. Prioritize systems that house your most sensitive data and coordinate with your infrastructure teams to verify if they have applied the latest vendor security updates.

References

www.oracle.com/security-alerts/cpujul2026.html

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.