External risk intelligence

Windows DHCP Client Stack Buffer Overflow Remote Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-44815

A critical stack-based buffer overflow vulnerability in the Windows DHCP Client enables unauthorized network attackers to execute code. This could compromise affected systems, impacting data confidentiality, integrity, and availability. Understanding this threat is vital for assessing environmental risks.

2Halo Surface Signal

Buffer Overflow

Microsoft Windows 10 1607

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External exposure likelihood

Halo Surface Signal score for CVE-2026-44815

The DHCP client is a fundamental network service present on almost all systems. While network-reachable within a local broadcast domain, it is designed to operate on local network segments and is typically blocked by firewalls and network perimeters from direct public internet exposure.

PCI scan relevance

PCI Relevance for CVE-2026-44815

Yes

CVE-2026-44815 — Halo PCI Relevance: Yes. Under typical PCI ASV external scan criteria, this issue may be flagged for scan prioritization.

A critical stack-based buffer overflow vulnerability in Windows DHCP Client allows for remote code execution, posing a significant risk to PCI compliance.

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

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in the Windows DHCP Client, potentially allowing unauthorized attackers to execute code over a network. This issue is notable due to its high severity and the widespread use of Windows operating systems. Understanding the nature of this threat is important for assessing potential risks to our environment.

  • Remote code execution vulnerability found.
  • Affects essential Windows networking functionality.
  • Confirm relevance and exposure in our environment.

Attack Path

How an attacker could exploit the issue

An attacker could exploit a stack-based buffer overflow vulnerability in the Windows DHCP Client to execute arbitrary code. This attack can be launched remotely over a network, requiring no special privileges or user interaction. Successful exploitation could lead to a complete compromise of the affected system.

  • No authentication required.
  • Remote network trigger.
  • Arbitrary code execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an unauthorized attacker to execute code over a network when the Windows DHCP Client is accessible. This could potentially affect system integrity and the confidentiality and availability of system data.

  • System data could be affected.
  • Code execution over a network.
  • Loss of system integrity.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This critical vulnerability in the Windows DHCP Client requires immediate attention, likely involving infrastructure and network security teams. The first step is to identify all DHCP clients within your environment, determine their network exposure, and confirm their business criticality. Once ownership is established, a risk-based remediation plan can be developed.

  • Infrastructure and network security teams own this.
  • Verify DHCP client network exposure and criticality.
  • Plan remediation based on identified risk.

Frequently asked questions

What is the Windows DHCP Client and why is it used?

The Windows DHCP Client is a background system service responsible for automatically managing network configuration. It enables computers to dynamically obtain an IP address and other network settings from a server, which simplifies connectivity and eliminates the need for manual network setup across corporate and home environments.

What does CWE-121 mean for CVE-2026-44815?

CWE-121 refers to a stack-based buffer overflow. In the context of this CVE, it means the DHCP client fails to properly check the size of incoming network data before copying it into a specific memory area called the stack. If an attacker sends specially crafted, oversized data, it can overwrite adjacent memory, potentially allowing them to hijack the system's execution flow and run unauthorized commands.

How is this vulnerability triggered by an attacker?

An attacker triggers this flaw by sending malicious data to the DHCP client over the network. Because the service listens for communications to manage network settings, it processes this input automatically. Importantly, this does not require a user to click a link or open a file; the vulnerability resides in how the system handles lower-level networking protocols before any application-level interaction occurs.

Do I need to worry about this if my systems are internal?

According to Halo Surface Signal, this vulnerability is deemed unlikely to be exploited from the public internet because the DHCP client is designed for local broadcast domains and is typically blocked by firewalls. While your internal network is the primary area of concern, the risk is highest on systems that are not protected by robust internal network segmentation.

What are the first steps to address this CVE?

Begin by identifying which assets in your environment run the Windows DHCP Client service. Once you have a list, coordinate with your network security teams to verify how these devices are positioned within your network segments. Finally, use this inventory to prioritize risk management, focusing on high-value systems that lack adequate perimeter or internal network defenses.

References