External risk intelligence

Linux Kernel Ethernet Driver port_id Extraction Flaw Causes Crashes.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-74737

The vulnerability exists within low-level Linux kernel networking driver code for a specific Ethernet switch peripheral. It involves internal packet metadata processing and is not an internet-facing service, application, or gateway that would be exposed to or reachable from the public internet in standard deployments.

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A recent issue has been identified in the Linux kernel affecting networking components, specifically how certain packet data is processed. This could lead to unpredictable system behavior. The main concern is to confirm if our specific systems utilize this particular networking functionality.

Invalid packet data causes system instability.
This affects low-level networking functions.
Confirm relevance and exposure of specific systems.

Attack Path

How an attacker could exploit the issue

An attacker could trigger a kernel crash by sending specially crafted network packets to a vulnerable system. This occurs because the system incorrectly extracts a port identifier from received network data, leading it to access memory it shouldn't. The consequences of this out-of-bounds memory access are severe, potentially allowing an attacker to disrupt system stability and cause denial of service.

Network access required.
Malformed network packets trigger vulnerability.
Kernel crash leading to denial of service.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in the Linux kernel's network driver for the AM65-CPSWNUSS Ethernet peripheral could lead to a kernel crash. This crash may occur when processing incoming network packets due to incorrect extraction of the MAC port identifier from packet metadata. The issue is specific to the internal handling of packet reception and is not directly related to user data or PII.

Kernel stability.
Incorrect port ID processing.
System crash.

Operational Fix

Recommended remediation, mitigation, and detection steps

Teams responsible for Linux kernel infrastructure, particularly those managing embedded systems or network devices utilizing the AM65-CPSWNUSS Ethernet peripheral, should lead the response. The initial practical step involves identifying all deployments of this specific kernel component, assessing their reachability and business criticality, and locating the accountable owner to initiate a risk-based remediation plan.

Kernel and Infrastructure teams should own.
Verify affected systems and exposure.
Plan targeted updates during maintenance.

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 the AM65-CPSWNUSS Ethernet peripheral in the Linux kernel?

The AM65-CPSWNUSS is a specific Ethernet switch component found in certain Texas Instruments processors. It is managed by a low-level driver within the Linux kernel responsible for handling network traffic. When a packet arrives, the driver extracts metadata to determine which physical port received it. This process is essential for routing traffic correctly through the hardware interfaces of the device, typically found in embedded networking or industrial control systems.

How does this vulnerability manifest as a memory error?

This flaw is a type of out-of-bounds access error. The driver mistakenly treats a 16-bit value as a port identifier, even though only the lower 8 bits are valid for that purpose. Because the remaining bits contain arbitrary hardware data, the driver uses an invalid, potentially massive number to index memory. This causes the kernel to attempt to read or write to unauthorized areas of system memory, leading to unpredictable behavior or a complete system crash.

Do I need a malicious payload to trigger this crash?

Yes, an attacker must send specially crafted network packets to the device to trigger this behavior. The vulnerability relies on the system receiving a packet that the driver processes through the affected identification logic. It is important to note that simply having the network interface connected or passing standard, valid traffic does not inherently trigger this issue; it requires the specific, malformed metadata that causes the driver to misinterpret the port ID.

Is my system vulnerable according to Halo Surface Signal?

Halo Surface Signal indicates that this vulnerability is very unlikely to be reachable from the public internet. Because the issue resides in low-level driver code for a specific Ethernet peripheral rather than an internet-facing application or gateway, standard deployments are not directly exposed. While the threat to internal stability is real if an attacker gains network proximity, the risk of external exploitation is significantly lower due to the nature of the affected component.

What should I do if I manage systems using this driver?

Your first step is to identify all hardware deployments utilizing the AM65-CPSWNUSS Ethernet peripheral within your infrastructure. You do not need to hunt for active exploits; instead, focus on inventory management to locate systems running the vulnerable kernel version. Once identified, coordinate with your kernel and infrastructure teams to plan a standard update cycle to apply the necessary kernel patch during your next scheduled maintenance window.

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.