CVE-2026-65785 in Windows
Summary
by MITRE • 08/12/2026
Uncontrolled resource consumption in Windows DHCP Client allows an unauthorized attacker to deny service over an adjacent network.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical denial of service condition within the windows dhcp client implementation that can be exploited by unauthorized attackers positioned on the same network segment. The flaw stems from insufficient input validation and resource management within the dhcp client component that processes responses from dhcp servers, allowing malicious actors to craft specially crafted dhcp messages that consume excessive system resources. The vulnerability specifically manifests when the dhcp client receives malformed or excessively large dhcp offers, acks, or nak messages that trigger unbounded memory allocation or processing loops. This issue directly aligns with cwe-400 which categorizes unchecked resource consumption as a fundamental weakness in software design where systems fail to properly monitor and limit resource usage. The attack surface is particularly concerning for adjacent network environments where attackers can leverage the broadcast nature of dhcp communications to execute their payloads without requiring authentication or prior system compromise.
The technical exploitation of this vulnerability leverages the inherent characteristics of dhcp protocol communication patterns where clients must process and respond to dhcp server messages in real time. When an attacker sends malformed dhcp responses with excessive options, oversized data fields, or recursive message structures, the windows dhcp client component enters into resource-intensive processing states that can lead to memory exhaustion, cpu saturation, or complete service unavailability. This behavior aligns with attack techniques documented in the att&ck framework under initial access and privilege escalation categories where adversaries establish persistent network presence to facilitate broader attacks. The impact extends beyond simple denial of service as it can disrupt critical network infrastructure dependencies, potentially affecting network operations, system availability, and enterprise productivity. Network administrators may observe symptoms including dhcp client failures, network connectivity issues, or complete loss of network services in affected segments.
The operational implications of this vulnerability are severe for organizations relying on windows-based dhcp implementations, particularly in enterprise environments where dhcp is fundamental to network operations. Attackers can exploit this weakness using readily available tools to generate dhcp traffic that consumes system resources at rates exceeding normal operational parameters. The vulnerability affects multiple windows versions including server and client operating systems where dhcp client functionality remains active. Organizations may experience cascading failures as affected systems become unresponsive, potentially leading to extended downtime while administrators investigate and remediate the issue. The resource consumption patterns can be particularly challenging to detect through standard monitoring tools since they often appear as normal network activity until system performance degradation becomes noticeable.
Mitigation strategies should focus on implementing network-level controls and system hardening measures that address the root causes of this vulnerability. Network segmentation through vlan configurations and dhcp snooping can limit the scope of exploitation by restricting broadcast domains and preventing unauthorized dhcp server responses from reaching client systems. System administrators should implement dhcp client configuration restrictions including limiting option processing, setting maximum message size limits, and enabling resource monitoring for abnormal consumption patterns. The implementation of network access control lists and port security measures can further reduce attack surface by preventing unauthorized devices from participating in dhcp communications. Regular system updates and patches addressing this specific vulnerability should be prioritized as part of comprehensive security maintenance protocols. Additionally organizations should consider implementing intrusion detection systems that can identify abnormal dhcp traffic patterns and alert administrators to potential exploitation attempts. The remediation approach must align with industry best practices for dhcp security and should include monitoring for resource consumption anomalies that could indicate active exploitation of this vulnerability.