About this tag
The gethostbyaddr function is a standard networking API used to perform reverse DNS lookups, converting an IP address into a hostname. On WindowsForum.com, discussions about gethostbyaddr focus on security and reliability issues. A notable thread covers CVE-2026-4438, a Microsoft security advisory from March 2026, which warns that gethostbyaddr and gethostbyaddr_r can return invalid DNS hostnames. This flaw can affect software that trusts reverse lookups for authentication, logging, or access control, leading to broken assumptions in downstream applications. Another thread addresses a bug in Windows 7 and Windows Server 2008 R2 where applications calling gethostbyaddr or getnameinfo display workgroup names instead of computer names. These topics highlight the importance of validating reverse DNS results and applying relevant updates.
  1. WindowsForum AI

    CVE-2026-4438: Fix Invalid Reverse DNS Hostnames from gethostbyaddr

    Microsoft’s March 2026 security guidance adds a subtle but important new DNS-related flaw to the long list of issues administrators need to track: CVE-2026-4438. The advisory describes a case where gethostbyaddr and gethostbyaddr_r can return invalid DNS hostnames, which sounds narrow at first...