External risk intelligence

Linux Kernel rxgk Integer Overflow Vulnerability.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-46039

A Linux kernel vulnerability has been fixed that could lead to an integer overflow during a length check, potentially impacting system integrity and availability. The issue involves the `rxgk` component's handling of ticket lengths. It is uncertain if this internal function is reachable or relevant in your specific env

2Halo Surface Signal

Integer Overflow

Linux Kernel

6.16.9 to before 6.176.17.1 to before 6.18.276.19 to before 7.0.46.17

External exposure likelihood

Halo Surface Signal score for CVE-2026-46039

This vulnerability exists in an internal Linux kernel function (rxgk) related to token extraction. While the kernel is network-reachable, this specific component is not typically exposed directly to the public internet and usually requires specific, non-default networking configurations or protocols to be reachable from an external context.

PCI scan relevance

PCI Relevance for CVE-2026-46039

Yes

CVE-2026-46039 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

This Linux kernel vulnerability involves an integer overflow that could lead to a bypass of security checks, making it relevant for PCI scans.

Scan-prioritization guidance only—not a PCI DSS certification or ASV attestation.

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in the Linux kernel has been addressed that could allow for an integer overflow during a length check. This issue relates to how ticket length is processed, and the fix involves adjusting how available data size is calculated to prevent potential overflow. The primary concern is to confirm whether this specific internal kernel function is relevant and exposed within your environment.

Kernel function error found.
Confirm if this internal component is exposed.
Assess relevance and potential exposure.

Attack Path

How an attacker could exploit the issue

An attacker could reach the vulnerable code in the Linux kernel through network access, exploiting an integer overflow in a length check within the `rxgk_extract_token()` function. This flaw, if triggered, could allow an attacker to compromise the confidentiality, integrity, and availability of the system.

Network access required.
Integer overflow in length check.
Allows system compromise.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could affect the integrity and availability of systems running the Linux kernel when processing specific network traffic. An integer overflow in a length check could lead to unexpected behavior or crashes.

System integrity and availability at risk.
Network traffic processing could trigger overflow.
System instability or data corruption may occur.

Operational Fix

Recommended remediation, mitigation, and detection steps

This Linux kernel vulnerability requires identification and prioritization by teams managing core operating system components. Start by locating all instances of the affected Linux kernel versions, assessing their exposure, and confirming business criticality. Once ownership is established, a risk-based remediation plan can be developed, potentially involving coordination with vendor support if applicable.

Own by Infrastructure/Platform teams.
Verify kernel exposure and business criticality.
Plan remediation during maintenance windows.

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 Linux kernel and how does it use rxgk?

The Linux kernel is the fundamental core of the operating system that manages hardware resources and provides essential services to software. Within it, rxgk is a component that handles specialized authentication or security tokens. It is typically responsible for extracting and validating these tokens during network communications to ensure secure data exchange between systems.

How does CVE-2026-46039 cause an integer overflow?

This vulnerability is classified as CWE-190, or integer overflow. It occurs when a calculation exceeds the maximum value a memory variable can hold. In this CVE, the flaw exists in the rxgk_extract_token() function. When the system checks the size of an incoming ticket, the logic previously attempted to round up values, which could wrap around to a very small number and bypass critical security checks.

Do I need network traffic to trigger this flaw?

Yes, an attacker must send specific network traffic that reaches the rxgk_extract_token() function to trigger the flaw. However, standard or typical network interactions do not automatically activate this code path. The bug requires the system to be processing specific types of tokenized data, and it is not triggered by simple, unrelated network packets or general traffic.

How do I know if my system is vulnerable?

According to Halo Surface Signal, this vulnerability is considered unlikely to be reachable for most users. Because the rxgk component is an internal kernel function, it usually is not exposed directly to the public internet. It generally requires specific, non-default networking configurations to be reachable. You should check if your systems utilize these specialized configurations that interact with rxgk tokens.

What are the first steps to address this kernel issue?

Begin by identifying all systems running the affected Linux kernel versions listed in the advisory. Once identified, evaluate if your specific use cases involve the rxgk component or custom network protocols that might reach this code. If your environment uses these features, prioritize patching during your next maintenance cycle and coordinate with your infrastructure team to apply the necessary kernel updates provided by your distribution vendor.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.