CVE-2026-69510: Windows 10 1607 Buffer Overflow Flaw

CVE-2026-69510 Overview

CVE-2026-69510 is a stack-based buffer overflow in the Windows DHCP Server service that allows an unauthenticated attacker to execute code over a network. The flaw is tracked as [CWE-121] and affects multiple supported Windows Server and Windows 10 releases. Microsoft published the advisory on 2026-09-08 with a base score of 8.1 (High).

Successful exploitation grants code execution in the context of the DHCP Server service, which typically runs with elevated privileges on domain infrastructure hosts. The advisory indicates high attack complexity, meaning exploitation requires specific conditions such as race timing or memory layout constraints.

Critical Impact
Unauthenticated network attackers can achieve remote code execution on Windows DHCP Servers, compromising core network infrastructure and enabling lateral movement across the enterprise.

Affected Products

Microsoft Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025
Microsoft Windows 10 version 1607 (x86 and x64)
Microsoft Windows 10 version 1809 (x86 and x64)

Discovery Timeline

2026-09-08 - Microsoft publishes advisory for CVE-2026-69510
2026-09-08 - CVE-2026-69510 published to the National Vulnerability Database
2026-09-09 - Last updated in the NVD database

Technical Details for CVE-2026-69510

Vulnerability Analysis

The vulnerability resides in the Windows DHCP Server service, which processes Dynamic Host Configuration Protocol messages on UDP port 67. A malformed request triggers a stack-based buffer overflow inside the message-parsing path. An attacker who exploits the flaw executes code with the privileges of the DHCP Server process.

Because DHCP servers frequently run on domain controllers or adjacent infrastructure hosts, code execution here can provide a foothold for broader Active Directory compromise. The advisory notes high attack complexity, suggesting the overflow requires specific conditions such as precise timing, controlled memory state, or a particular network position. No authentication or user interaction is required.

Root Cause

The defect is a classic [CWE-121] stack-based buffer overflow. The DHCP Server writes attacker-influenced data past the bounds of a fixed-size stack buffer during protocol message handling. This corrupts adjacent stack memory, including saved return addresses and structured exception handler records, enabling control-flow hijack.

Attack Vector

The attack vector is the network. An attacker sends crafted DHCP packets to a vulnerable server that reaches the DHCP Server service. Exploitation typically requires the attacker to be on a network segment where DHCP traffic is accepted, such as an internal LAN or a segment reachable through a relay agent. See the Microsoft CVE-2026-69510 Advisory for vendor-supplied technical details.

No verified public exploit code is available at this time. A prose description of the mechanism is provided above in place of proof-of-concept code.

Detection Methods for CVE-2026-69510

Indicators of Compromise

Unexpected crashes or restarts of the DHCPServer service (dhcpssvc.dll) on Windows Server hosts.
Anomalous DHCP packets containing oversized option fields or malformed vendor-specific information.
Unexplained child processes spawned by svchost.exe hosting the DHCP Server service.
Outbound network connections originating from the DHCP Server process to unfamiliar destinations.

Detection Strategies

Monitor Windows Event Log for DHCP Server service errors, Application Error events (Event ID 1000), and Windows Error Reporting entries referencing dhcpssvc.dll.
Deploy network intrusion detection signatures that flag oversized or protocol-noncompliant DHCP option fields on UDP port 67.
Baseline DHCP server process behavior and alert on any process creation or file write activity by the DHCP Server service.

Monitoring Recommendations

Collect Sysmon process creation and network connection events from all DHCP Server hosts and forward them to a centralized log platform.
Track DHCP Server service start, stop, and crash events, and correlate with inbound packet captures from the same window.
Alert on any interactive logon or lateral movement attempts originating from DHCP Server hosts following service anomalies.

How to Mitigate CVE-2026-69510

Immediate Actions Required

Apply the Microsoft security update referenced in the Microsoft CVE-2026-69510 Advisory to all affected Windows Server and Windows 10 systems.
Inventory hosts running the DHCP Server role using Get-WindowsFeature DHCP and prioritize domain-joined and internet-adjacent servers.
Restrict inbound DHCP traffic to trusted network segments and relay agents through firewall and switch access control lists.

Patch Information

Microsoft has released security updates for all affected products. Consult the Microsoft CVE-2026-69510 Advisory for the specific KB articles applicable to each Windows Server and Windows 10 build. Apply updates through Windows Update, WSUS, or Microsoft Update Catalog.

Workarounds

If patching cannot occur immediately, consider temporarily stopping the DHCP Server service on non-essential hosts using Stop-Service DHCPServer.
Segment DHCP servers onto isolated management VLANs and block DHCP traffic from untrusted subnets at the perimeter.
Enable DHCP snooping and rogue DHCP detection on network switches to limit which sources can send DHCP packets to server ports.

bash

# Configuration example: restrict DHCP traffic with Windows Firewall
New-NetFirewallRule -DisplayName "Restrict DHCP Server Inbound" `
  -Direction Inbound `
  -Protocol UDP `
  -LocalPort 67 `
  -RemoteAddress 10.0.0.0/24 `
  -Action Allow

# Block DHCP inbound from all other sources
New-NetFirewallRule -DisplayName "Block DHCP Server Untrusted" `
  -Direction Inbound `
  -Protocol UDP `
  -LocalPort 67 `
  -Action Block