Samba WINS Server NULL Pointer Dereference Vulnerability

Executive Summary

CVE-2026-3238 is a vulnerability in Samba's WINS server component when it is running as an Active Directory Domain Controller. The issue occurs because the WINS protocol handlers do not properly validate certain incoming UDP packets. This allows an unauthenticated remote attacker to send specially crafted packets that trigger a NULL pointer dereference, causing the WINS service to crash.

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Impact Analysis

This vulnerability can lead to a denial of service (DoS) condition by crashing the WINS service on an Active Directory Domain Controller. Since the attacker does not need to be authenticated, they can remotely disrupt the availability of the WINS service, potentially impacting network name resolution and domain controller functionality.

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Compliance Impact

The vulnerability in Samba's WINS server component allows an unauthenticated remote attacker to cause a denial of service by crashing the WINS service. This results in availability disruption of the Active Directory Domain Controller's WINS service.

While the vulnerability impacts service availability, there is no indication from the provided information that it leads to unauthorized access, data disclosure, or data integrity issues.

Therefore, the direct impact on compliance with data protection regulations such as GDPR or HIPAA, which primarily focus on confidentiality and integrity of personal data, is limited to potential availability concerns.

Organizations relying on Samba AD DC WINS services should consider the risk of denial of service in their availability controls and incident response plans to maintain compliance with standards that require system availability.

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Detection Guidance

This vulnerability can be detected by monitoring for crashes or service interruptions of the Samba WINS server component running as an Active Directory Domain Controller. Since the issue is triggered by specially crafted UDP packets causing a NULL pointer dereference, network traffic analysis focusing on unusual or malformed UDP packets targeting the WINS service port may help identify exploitation attempts.

Specific commands or detection tools are not provided in the available resources.

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Mitigation Strategies

Immediate mitigation steps are not explicitly detailed in the provided resources. However, general best practices include restricting UDP traffic to the WINS service from untrusted networks, applying any available patches or updates from Samba or your distribution vendor once released, and monitoring the WINS service for crashes or abnormal behavior.

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