CVE-2026-69547 in Windows
Summary
by MITRE • 09/09/2026
Heap-based buffer overflow in Windows DHCP Server allows an authorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability described constitutes a critical security flaw within the Dynamic Host Configuration Protocol (DHCP) server service on Microsoft Windows operating systems, specifically classified as a heap-based buffer overflow. This type of memory corruption error occurs when a program writes data beyond the allocated boundaries of a buffer located in the heap segment of computer memory. In the context of the DHCP server, this flaw is triggered during the processing of specific network packets or configuration parameters that are not adequately validated for length or structure before being copied into fixed-size buffers. The presence of such an overflow allows malicious actors to overwrite adjacent memory locations with carefully crafted data, potentially altering program execution flow and gaining control over critical system functions.
From a technical perspective, heap-based buffer overflows are particularly dangerous because the heap is used for dynamic memory allocation during runtime. When an attacker exploits this vulnerability, they can manipulate pointers or function return addresses stored in nearby memory regions. By injecting shellcode or leveraging existing code within the process space through techniques like Return Oriented Programming (ROP), the attacker achieves arbitrary code execution with the privileges of the DHCP service account. Since the DHCP server typically runs under high-privilege system accounts, successful exploitation grants the attacker full control over the affected machine, enabling them to install programs, view, change, or delete data, and create new administrative accounts.
The operational impact of this vulnerability is severe due to its network-accessible nature. An authorized attacker can exploit this flaw remotely without requiring local access to the target system first. This means that any host running a vulnerable version of Windows with the DHCP server role enabled is exposed to remote code execution attacks over standard IP networks. The ability to execute code as SYSTEM level privileges effectively compromises the integrity, confidentiality, and availability of the entire network infrastructure managed by that server. Attackers can use this foothold to pivot laterally across the network, escalate privileges further, or deploy ransomware and other malware payloads with minimal resistance from traditional perimeter defenses.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) identifier CWE-120, which describes buffer copy without checking size limits, a fundamental category of memory safety errors. Furthermore, in the context of the MITRE ATT&CK framework, this exploitation path maps to techniques such as Tactic TA0004 Privilege Escalation and Technique T1059 Command and Scripting Interpreter, where the initial code execution serves as a vector for deeper system compromise. The lack of proper bounds checking on input data from network sources represents a classic failure in secure coding practices, highlighting the necessity for rigorous validation mechanisms in services that process external inputs.
Mitigation strategies must focus primarily on applying vendor-supplied security patches to update the DHCP server components and underlying operating system libraries. Organizations should immediately verify their inventory of Windows servers running the DHCP role and ensure they are patched with the latest cumulative updates released by Microsoft. In environments where patching is not immediately feasible, network segmentation can provide a temporary layer of defense by restricting access to the DHCP service ports from untrusted networks. Additionally, implementing strict input validation rules in custom applications that interact with the DHCP API or configuring firewalls to limit exposure to only necessary client subnets can reduce the attack surface. Continuous monitoring for anomalous network traffic patterns indicative of exploitation attempts is also recommended to detect potential breaches early.