CVE-2026-85903

Summary

This CVE describes an untrusted pointer dereference vulnerability in Microsoft's DNS Server that allows remote attackers to execute arbitrary code on affected Windows systems. The flaw occurs when processing DNS requests, making it particularly dangerous for network infrastructure services.

Exploitability

Exploitation is moderately difficult as it requires a remote attacker to send specially crafted DNS packets to an affected system, but the attack surface is broad since DNS servers are commonly exposed to untrusted networks.

Blast radius

If exploited, this vulnerability could allow attackers to gain full control over affected DNS servers, potentially enabling them to redirect traffic, perform man-in-the-middle attacks, or compromise entire network infrastructures that rely on those DNS services.

Detection

Monitor for unusual DNS query patterns or malformed DNS responses in network traffic logs, particularly looking for DNS server processes handling unexpected packet structures that could indicate exploitation attempts.

Prioritized remediation

Apply the Microsoft security update KB5042819 for Windows 10 version 1607, Windows 10 version 1809, Windows 10 version 21H2, Windows 10 version 22H2, Windows 11 version 23H2, Windows 11 version 24H2, and Windows 11 version 25H2.

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.