External risk intelligence

Windows DHCP Server Heap Buffer Overflow Remote Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-50518

The vulnerability affects a DHCP server, which is a network-layer service typically restricted to local area networks or internal corporate segments. While network-reachable within an environment, it is not designed to be exposed directly to the public internet in common, secure deployment patterns.

Buffer Overflow

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory details a critical security flaw found in Windows DHCP Server. The vulnerability, identified as a heap-based buffer overflow, could enable an unauthorized attacker to execute code remotely across a network, potentially leading to a significant compromise of systems. The primary concern at this stage is to confirm if your environment utilizes the affected technology and determine the extent of any potential exposure.

Flaw allows remote code execution.
Understand if your network uses this technology.
Confirm relevance and assess potential exposure.

Attack Path

How an attacker could exploit the issue

An attacker could reach a vulnerable Windows DHCP server over a network without needing any special privileges or user interaction. By sending specially crafted network requests, they could trigger a flaw in the DHCP server, potentially allowing them to run their own code on the affected system.

No privileges or user interaction needed.
Triggered by network requests to DHCP server.
Allows unauthorized code execution.

Live Threat

Current exploitation, exposure, and threat context

A heap-based buffer overflow in Windows DHCP Server could allow an unauthorized remote attacker to execute code over a network when supported by the advisory's conditions. This could impact the confidentiality, integrity, and availability of the DHCP service.

DHCP server code execution.
Remote network access.
Service disruption or compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

Real-World Ownership

This critical vulnerability in Windows DHCP Server requires immediate attention from teams responsible for core network infrastructure. The first step is to confirm the presence and reachability of affected DHCP servers within your environment. Subsequently, identify the accountable owner, assess the business criticality of these systems, and then prioritize remediation actions based on the potential for network-based code execution.

Infrastructure and Network teams own this.
Verify DHCP server network exposure and criticality.
Plan and execute prioritized remediation actions.

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 Windows DHCP Server?

Windows DHCP Server is a core networking service included in Windows Server operating systems. Its primary role is to automatically assign IP addresses and network configuration parameters, such as default gateways and DNS settings, to computers and devices as they connect to a network. By managing these assignments centrally, it ensures that devices can communicate efficiently without requiring manual network configuration on every individual client.

What does CVE-2026-50518 mean by heap-based buffer overflow?

This vulnerability is classified as CWE-122, a heap-based buffer overflow. In plain terms, this means the software incorrectly handles memory when processing data. An attacker can send a specially crafted network request that forces the DHCP service to write more data into a specific area of memory, known as the heap, than it is designed to hold. This overflow can overwrite adjacent memory, which may allow the attacker to inject and execute their own unauthorized code on the server.

How is this Windows DHCP Server vulnerability triggered?

An attacker triggers this flaw by sending malicious network requests directly to the DHCP server. Because the service is designed to accept requests from various devices on the network, it does not require the attacker to have any special user privileges or access credentials. It is important to note that this bug is triggered by legitimate-looking DHCP communication patterns being used maliciously; normal, non-malicious network traffic does not cause this memory error.

Is my network at risk from this CVE?

According to Halo Surface Signal, this vulnerability is unlikely to be reachable from the public internet. Windows DHCP servers are typically intended to operate within local area networks or internal corporate segments. While the vulnerability is network-reachable for anyone who has access to your internal environment, it is generally not designed or expected to face the public internet, which limits the attack surface for external threats.

What should I do first to manage this threat?

Your priority is to identify every Windows Server in your environment that has the DHCP role enabled. Once you have an inventory of these systems, verify which of them are accessible over your internal network. Because this flaw allows for remote code execution, work with your infrastructure and network teams to assess the criticality of these servers and prepare to apply patches or mitigations as soon as they become available from the vendor.

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50518

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.