External risk intelligence

Linux Kernel Open vSwitch Use-After-Free Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-98490

The vulnerability exists in the Linux kernel's Open vSwitch conntrack module, which processes network traffic. While this component is used in infrastructure and cloud environments that often handle public traffic, the specific code path involves internal connection tracking and memory management rather than a public-facing service endpoint. Exposure is possible depending on system configuration, but not inherently public.

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A security vulnerability has been identified in the Linux kernel's networking components, specifically within the Open vSwitch conntrack module. This issue relates to how network connection tracking information is managed, potentially leading to system instability or unauthorized access if exploited. The primary concern is confirming whether our specific environments are affected by this particular flaw in network traffic processing.

Flaw in network traffic tracking.
Important for internal system stability.
Confirm relevance to our infrastructure.

Attack Path

How an attacker could exploit the issue

An attacker could reach this vulnerability by sending specially crafted network packets to a system running a vulnerable Linux kernel. This could lead to unexpected behavior or denial of service when the system attempts to manage network connection tracking extensions.

Network access to the system is required.
Specially crafted network packets trigger the issue.
Potential for system instability or denial of service.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in the Linux kernel's network processing could allow an attacker to cause a use-after-free condition in the connection tracking subsystem when handling network extensions. This may lead to system instability or unexpected behavior.

Network connection tracking data.
Use-after-free memory corruption.
System instability or crashes.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the Linux kernel's Open vSwitch conntrack module requires infrastructure or platform teams to identify affected systems. The first practical step is to determine the scope of exposure by locating all instances of the affected kernel component, assessing their reachability and criticality, and identifying the accountable system owner before planning remediation.

Infrastructure/platform teams own the issue.
Verify conntrack reachability and system criticality.
Plan remediation based on confirmed exposure.

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.

Free EASM Trial See How Signal Works

Frequently asked questions

What is the Linux kernel Open vSwitch conntrack module?

Open vSwitch is a virtual switch used in cloud and virtualized environments to manage network traffic between virtual machines and containers. The conntrack module, or connection tracking, is a specific part of this system that monitors the state of network connections. It keeps track of packet flow and metadata, helping the kernel make decisions about how to route, filter, or process incoming and outgoing traffic efficiently across complex virtual networks.

How does this CVE-2026-98490 memory issue happen?

This vulnerability is a use-after-free weakness. It occurs because the kernel may reallocate memory for connection extensions while a pointer to that memory is still being used by the expectation list. When the system later tries to access that pointer, it refers to invalid or reassigned memory. By triggering this logic flaw, an attacker could cause memory corruption, potentially leading to system instability or crashes within the network processing subsystem.

What must happen for this bug to be triggered?

An attacker needs to send specific, crafted network packets to a system that utilizes the Open vSwitch conntrack feature. The condition is triggered during the connection tracking process when helper functions are called while extensions are being reallocated. Simply sending standard or valid network traffic does not trigger the bug, as it requires a precise sequence of operations within the connection tracking lifecycle to leave an invalid pointer in the expectations list.

Is my system at risk if it runs Open vSwitch?

Halo Surface Signal indicates that while this vulnerability affects the Open vSwitch module, it is not inherently public-facing. The vulnerability exists deep within internal connection tracking memory management rather than at a public service endpoint. Your risk depends on your specific system configuration and how your network traffic is processed. If your infrastructure handles untrusted traffic, your exposure is higher than in isolated, internal-only environments.

How should I respond to CVE-2026-98490?

The first step is to identify all systems in your environment that are running the affected Linux kernel with Open vSwitch enabled. You do not need to take immediate emergency action, but you should inventory these assets, assess their criticality, and determine if they handle external traffic. Once you have identified the accountable teams and confirmed the presence of the component, you can plan for necessary kernel updates or security patches provided by your OS vendor.

References

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.