CVE-2026-70124 in Windows
Summary
by MITRE • 09/09/2026
Out-of-bounds read in Windows DHCP Server allows an unauthorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as an out-of-bounds read within the Microsoft Dynamic Host Configuration Protocol (DHCP) server service represents a critical memory safety flaw that compromises the confidentiality of system data. This specific defect occurs when the DHCP server processes specially crafted network packets, leading to an attempt to access memory locations beyond the intended buffer boundaries. Because this is classified as an out-of-bounds read rather than a write operation, it does not typically allow for arbitrary code execution or direct remote control of the affected system. Instead, its primary consequence lies in the unauthorized disclosure of sensitive information stored in adjacent memory regions that are accessed erroneously during packet parsing operations.
From a technical perspective, this flaw aligns with Common Weakness Enumeration (CWE) category CWE-125, which describes out-of-bounds read vulnerabilities where software reads data past the end or before the beginning of the intended buffer. In the context of Windows DHCP Server, the vulnerability likely stems from insufficient validation of packet length fields or malformed header structures within incoming UDP traffic on port 67 and 68. When an attacker sends a maliciously constructed request that triggers this boundary condition, the server may return data containing fragments of its own memory state to the network. This behavior effectively turns the DHCP service into a vector for information leakage, allowing remote attackers to extract potentially valuable system details without needing authentication or prior access privileges.
The operational impact of this vulnerability is significant due to the widespread deployment of Windows-based servers in enterprise environments acting as central infrastructure components for IP address management and network configuration. An unauthorized attacker positioned on the same local area network segment can exploit this flaw remotely by sending crafted packets over UDP. The ability to disclose information from server memory can aid attackers in further reconnaissance activities, such as identifying running processes, extracting cryptographic keys, or gathering data that facilitates more sophisticated attacks like privilege escalation or lateral movement within the network. This aligns with ATT&CK technique T1046, Network Service Discovery, where adversaries probe for services to gather information about the target environment before launching subsequent exploits.
Mitigation strategies must focus on both immediate remediation and long-term architectural defenses. The most effective countermeasure is to apply the latest security updates provided by Microsoft that patch this specific memory handling flaw in the DHCP server component. Organizations should prioritize deploying these patches across all Windows servers running the DHCP role, particularly those exposed to untrusted network segments or internet-facing interfaces if applicable. Additionally, implementing strict firewall rules to restrict UDP traffic on ports 67 and 68 to only authorized clients can reduce the attack surface by preventing unauthorized entities from sending crafted packets that trigger the vulnerability. Network segmentation should also be reviewed to ensure that DHCP servers are isolated in trusted zones where access is tightly controlled, thereby limiting the ability of potential attackers to interact with the service directly over the network.