CVE-2026-3238

A flaw was found in Samba’s WINS server component when running as an Active Directory Domain Controller. The WINS protocol handlers for certain request types did not properly validate incoming packets, allowing an unauthenticated remote attacker to trigger a NULL pointer dereference and crash the WINS service using specially crafted UDP packets.

This vulnerability affects the WINS server functionality in Samba Active Directory Domain Controller deployments.

A remote unauthenticated attacker may send specially crafted WINS packets that cause the WINS service to crash, resulting in denial of service. Although the service may automatically restart, the attack is trivial to repeat and can effectively make the WINS service continuously unavailable.

The vulnerable WINS functionality is not enabled by default and requires explicit activation using: "wins support = yes" setting in the [global] section of the smb.conf file.

The Samba package as shipped with Red Hat Enterprise Linux and other products is not affected by this issue as Red Hat doesn't provide the AD Domain Controller capability with it.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.