CVE-2024-38126: Windows 10 1507 NAT DOS Vulnerability

CVE-2024-38126 Overview

CVE-2024-38126 is a denial of service vulnerability in the Windows Network Address Translation (NAT) component. The flaw allows an unauthenticated remote attacker to disrupt the availability of the affected system by sending crafted network traffic. Microsoft addressed this issue during the August 2024 Patch Tuesday release. The vulnerability maps to [CWE-476] (NULL Pointer Dereference), indicating that the NAT driver fails to validate a pointer before dereferencing it during packet processing. Successful exploitation results in service disruption on Windows hosts and Windows Servers configured to forward or translate network traffic.

Critical Impact
Remote, unauthenticated attackers can trigger a denial of service condition against Windows NAT-enabled hosts without user interaction, impacting availability of network services routed through the affected systems.

Affected Products

Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
Microsoft Windows 11 (versions 21H2, 22H2, 23H2, 24H2)
Microsoft Windows Server 2012 R2, 2016, 2019, 2022, and 2022 23H2

Discovery Timeline

2024-08-13 - CVE-2024-38126 published to NVD
2024-08-13 - Microsoft releases security update addressing the vulnerability
2024-08-16 - Last updated in NVD database

Technical Details for CVE-2024-38126

Vulnerability Analysis

The vulnerability resides in the Windows Network Address Translation (NAT) implementation, which handles address rewriting for systems acting as network gateways or using Internet Connection Sharing. The NAT driver processes inbound packets and maintains translation tables for active sessions. The flaw is categorized as a NULL pointer dereference [CWE-476], meaning the component dereferences a pointer that was not properly validated against NULL before use.

An attacker who reaches a vulnerable NAT endpoint over the network can submit malformed or unexpected packet sequences that drive the NAT code path into a state where a required structure pointer remains uninitialized. When the driver subsequently accesses that pointer, the kernel triggers a bug check, halting the affected host. The attack requires no authentication, no user interaction, and low attack complexity.

Root Cause

The root cause is missing validation of a pointer within the NAT packet processing logic. Under specific traffic conditions, a code path dereferences a structure pointer without confirming successful allocation or lookup. This results in a kernel-mode NULL pointer dereference and a system crash on hosts where the NAT service handles the malicious traffic.

Attack Vector

Exploitation occurs over the network. An attacker sends specially crafted packets to a Windows system that has NAT functionality enabled, such as a Routing and Remote Access Service (RRAS) deployment, an Internet Connection Sharing host, or a Hyper-V virtual switch using NAT. Because the vulnerability impacts the kernel driver responsible for translation, exploitation causes a bug check and reboots the affected host, breaking connectivity for all clients behind the NAT gateway.

No public exploit code or proof-of-concept is currently available for CVE-2024-38126, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog. See the Microsoft Security Update Guide for vendor-supplied technical details.

Detection Methods for CVE-2024-38126

Indicators of Compromise

Unexpected kernel bug checks (BSOD) on Windows hosts running RRAS, Internet Connection Sharing, or Hyper-V NAT virtual switches
Repeated reboots of NAT gateway systems correlated with bursts of inbound traffic from a single or small set of source addresses
Loss of connectivity for downstream clients dependent on the affected NAT host

Detection Strategies

Monitor Windows Event Log for BugCheck events (Event ID 1001) on hosts performing NAT functions and correlate timestamps with network capture data
Inspect network flows for anomalous packet patterns directed at the external interface of NAT gateways immediately preceding crash events
Capture and review minidump files generated after kernel faults to identify NAT driver modules in the call stack

Monitoring Recommendations

Track availability and uptime metrics on all Windows systems performing NAT or RRAS roles
Alert on repeated unexpected reboots of network-edge Windows hosts
Ingest Windows kernel crash telemetry into a centralized SIEM for correlation with perimeter network logs

How to Mitigate CVE-2024-38126

Immediate Actions Required

Apply the Microsoft August 2024 security updates to all affected Windows 10, Windows 11, and Windows Server versions listed in the advisory
Inventory systems running NAT-related roles, including RRAS, Internet Connection Sharing, and Hyper-V NAT virtual switches, and prioritize them for patching
Restrict exposure of NAT interfaces to untrusted networks while patches are being deployed

Patch Information

Microsoft published fixes for CVE-2024-38126 on August 13, 2024 as part of the monthly security update cycle. Administrators should consult the Microsoft Security Update Guide for CVE-2024-38126 for the specific KB article numbers applicable to each Windows version and install them through Windows Update, WSUS, or other endpoint management tooling.

Workarounds

Disable the Windows NAT role on hosts where it is not strictly required until the patch can be applied
Place upstream firewall rules to filter unsolicited inbound traffic to NAT-enabled interfaces from untrusted sources
Where feasible, route traffic through dedicated network appliances instead of Windows-based NAT until systems are updated

bash

# Configuration example: list and disable RRAS where unused
Get-Service RemoteAccess
Set-Service -Name RemoteAccess -StartupType Disabled
Stop-Service -Name RemoteAccess -Force