A new vulnerability—CVE-2024-21126—has been discovered in the Portable Clusterware component of the Oracle Database Server. If you are running Oracle Database versions 19.3-19.23 or 21.3-21.14, your environment may be at risk. This article breaks down what you need to know: what’s vulnerable, how an attacker could exploit this flaw, and most importantly, how you can protect your systems.

What is CVE-2024-21126?

CVE-2024-21126 affects the Oracle Database Portable Clusterware component. This is crucial software for high-availability Oracle clusters, used in many enterprise setups.

Oracle Database Server: 19.3 through 19.23, and 21.3 through 21.14

The vulnerability is rated as “Easily exploitable” and can be abused remotely and unauthenticated—meaning an attacker doesn’t need to log in.

Scope Change: Yes. Attacks can impact other products connected to Clusterware.

- Impact: Partial Denial of Service (partial DOS) — attackers can disrupt some Clusterware functionality, potentially affecting cluster stability, failover, and services relying on the Clusterware.

CVSS Base Score: 5.8 (Availability impacts)

- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

How Could CVE-2024-21126 Be Exploited?

The issue arises from how Portable Clusterware processes DNS requests. Because the vulnerability connects to DNS resolution, an attacker with network access can send special DNS queries to the cluster node. These queries can cause the Clusterware component to hang or crash—leading to partial service outages.

Sends the request to the affected module or cluster node.

4. Clusterware component becomes partly unavailable—causing failures in failover, monitoring, or node status checks.
5. Indirect impact: Other database operations or applications dependent on Clusterware may experience disruptions.

While Oracle has not published a full PoC, DNS-based DOS exploits typically look like this in Python

import socket

# Target the Oracle Clusterware's DNS-resolving port—replace with actual values.
target = "192..2.5"       # IP address of the Oracle Database node
port = 53

# Crafted payload—this would need to match the bug-triggers in Oracle component.
dns_malformed_query = b'\xaa\xbb\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00' \
                      b'\x03bad\x03dns\x00\x00\xff\x00\x01'

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.sendto(dns_malformed_query, (target, port))

print("Malicious DNS query sent!")

> Note: The exact payload to trigger the bug is not public, but this shows how one could send malformed DNS packets to the Oracle Clusterware. Replace "192..2.5" with your target’s real IP.

Disrupts core availability features of the Database cluster.

- May impact other applications or workflows connected to the Oracle Clusterware—“scope change.”

Real-World Example

Imagine your business relies on Oracle clusters for mission-critical applications. A single malformed DNS query on the network could degrade your cluster’s performance or stability, impacting hundreds or thousands of users.

Patch Immediately:

Oracle has released security updates to address CVE-2024-21126. Apply the April 2024 Critical Patch Update (CPU) or newer for your Oracle Database deployments. See official Oracle Advisories.

Restrict Network Access:

Only allow trusted devices to communicate over the network with your Oracle Database Clusterware ports.

Monitor DNS Traffic:

Inspect and log inbound DNS queries to your Oracle infrastructure. Consider an intrusion detection system (IDS) for unusual patterns targeting cluster nodes.

References

- Oracle Critical Patch Update Advisory - April 2024
- NVD Entry for CVE-2024-21126
- Oracle Database Security Guide

Conclusion

CVE-2024-21126 is a medium-severity but easily-triggered denial-of-service vulnerability in popular Oracle Database deployments. Because it requires no auth or user interaction, it’s wise to patch as soon as possible and double-check your network controls. Even a small omission in DNS/network configuration could leave your database cluster exposed.

Stay secure: patch early, monitor often, and review Oracle advisories regularly!


*This post is exclusive, written in clear, simple language for database engineers and sysadmins who need quick and actionable insights on CVE-2024-21126.*

Timeline

Published on: 07/16/2024 23:15:12 UTC
Last modified on: 08/29/2024 20:36:00 UTC