External risk intelligence

Linux Kernel Lantiq Memory Corruption in RX Ring

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2021-47137

This vulnerability affects a specific Linux kernel network driver (Lantiq). Drivers operate at the kernel level and are not directly exposed to the internet. Interaction requires local access or a highly specific, non-standard network architecture, making public internet exposure of the vulnerable component extremely unlikely in common deployments.

Linux Kernel

4.20 to before 5.4.1245.5 to before 5.10.425.11 to before 5.12.95.13

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 vulnerability has been identified in the Linux kernel's network component, specifically within the Lantiq driver. This issue could lead to memory corruption if memory allocation fails, potentially impacting system stability and data integrity. The main concern is to confirm if this specific driver is in use within the organization's Linux systems.

  • A kernel flaw may corrupt system memory.
  • Check if this specific network driver is active.
  • Confirm relevance and exposure to Linux systems.

Attack Path

How an attacker could exploit the issue

An attacker could trigger this vulnerability by sending specially crafted network traffic to a system running a vulnerable Linux kernel. This traffic would target the Lantiq network driver, attempting to cause a failure in memory allocation or DMA mapping. If successful, an invalid memory address could be programmed, leading to memory corruption.

  • Requires network access.
  • Triggered by crafted network packets.
  • Results in memory corruption.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in the Linux kernel's network driver could lead to memory corruption when memory allocation or DMA mapping fails. This condition, when triggered, could allow an attacker to exploit the flaw and potentially impact system stability or integrity.

  • System memory could be corrupted.
  • Memory allocation failures could trigger corruption.
  • Potential for system instability or crash.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts the Linux kernel's networking component, specifically the Lantiq driver. Ownership likely resides with the infrastructure or platform teams responsible for managing the underlying operating system and its drivers, with potential involvement from network or security teams to assess exposure. The first practical step is to identify all systems running the affected Linux kernel versions, determine network reachability of the Lantiq driver on these systems, and confirm the business criticality of impacted services before planning remediation.

  • Infrastructure or platform teams own resolution.
  • Verify systems with affected kernel versions.
  • Plan remediation based on exposure risk.

Supplementary metadata

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 Lantiq driver?

The Linux kernel is the core foundation of an operating system, managing hardware resources. The Lantiq driver is a specific software component within this kernel that allows the system to communicate with Lantiq-based network hardware. This driver is typically found in embedded devices like routers and gateways that rely on specific Lantiq chipsets to process incoming and outgoing network data.

How does CVE-2021-47137 cause memory corruption?

This issue is classified as CWE-770, which involves software behavior when resource allocation fails. In this CVE, if the system cannot allocate enough memory for a network task, the Lantiq driver fails to handle the error correctly. Instead of safely dropping the request, it programs an invalid memory address. This mistake causes the system to write data to the wrong place in memory, potentially overwriting critical information and leading to instability.

Can any network traffic trigger this Lantiq driver bug?

Not every packet will trigger this issue. The vulnerability specifically occurs when the driver encounters a memory allocation or DMA mapping failure during network processing. It is not triggered by standard, healthy network traffic. An attacker must send specially crafted packets that induce these specific failure conditions within the driver's internal RX (receive) ring operations to cause the memory corruption.

Why is this CVE considered unlikely to be internet-facing?

According to Halo Surface Signal, this vulnerability is very unlikely to be exposed to the public internet. While the CVSS score is high, the flaw exists within a specific low-level kernel driver. Drivers reside deep within the system stack and do not interact directly with the internet in the same way an application does. Success usually requires local access or a highly specific, non-standard network setup, which is rare for most standard deployments.

What steps should I take if I use this technology?

First, verify if your Linux systems are running one of the affected kernel versions mentioned in the advisory. Second, determine if those systems actually utilize the Lantiq network driver, as the code may be present but inactive. If the driver is in use, coordinate with your infrastructure or platform team to review kernel update schedules, which typically include the necessary fixes for these types of driver-level stability issues.

References

Sources and related resources

Primary sources: NVD, CVE.org.

NVDPublished Modified