CVE-2026-69929 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 on affected Windows operating systems. This specific defect occurs when the DHCP server processes specially crafted network packets, leading to a scenario where the application attempts to access memory locations beyond the intended buffer boundaries. Because this is an out-of-bounds read rather than a write operation, the primary consequence is not immediate code execution or system instability in the traditional sense of a crash, but rather the potential leakage of sensitive information stored in adjacent memory regions. An attacker who can interact with the DHCP service over the network may exploit this flaw to retrieve arbitrary data from the server's memory space, which could include cryptographic keys, session tokens, internal IP configurations, or other proprietary system details that were not intended for public disclosure.
From a technical perspective, this vulnerability aligns closely with Common Weakness Enumeration (CWE) category CWE-125, which describes out-of-bounds read vulnerabilities where software reads data past the end of a buffer. The root cause typically stems from insufficient validation of input parameters or incorrect calculation of array indices during packet parsing routines within the DHCP server component. When an unauthorized actor sends maliciously constructed requests to port 67 or 68, they can trigger this memory access violation. While out-of-bounds reads are often considered less severe than buffer overflows that allow for arbitrary code execution, their impact on confidentiality is significant and cannot be understated in enterprise environments where DHCP servers manage critical network infrastructure assets. The ability to exfiltrate internal state information facilitates further reconnaissance activities by adversaries seeking to map the network topology or identify additional attack vectors against connected devices.
The operational impact of this vulnerability extends beyond simple data leakage, as it undermines the trust model inherent in dynamic IP address assignment services. DHCP servers are fundamental to network operations, handling lease negotiations and configuration parameters for a vast number of endpoints. If an attacker can successfully exploit this flaw, they gain a foothold that allows them to gather intelligence without triggering typical intrusion detection systems associated with more aggressive exploits like remote code execution attempts. This stealthy nature makes the vulnerability particularly dangerous in long-term threat scenarios where adversaries aim to maintain persistent access and slowly escalate privileges or move laterally across the network segment managed by the compromised DHCP server. The disclosure of internal information can also aid attackers in crafting more sophisticated phishing campaigns or bypassing security controls that rely on specific IP ranges or MAC addresses for whitelisting decisions.
Mitigation strategies must prioritize immediate patching to address the underlying memory safety issues within the DHCP service binaries. Organizations should apply the latest cumulative updates provided by Microsoft, which contain corrections for this out-of-bounds read condition. In addition to software remediation, network segmentation plays a crucial role in limiting exposure. Since the attack vector requires network access to the DHCP server, restricting direct connectivity from untrusted networks or external internet sources via firewalls and Access Control Lists (ACLs) significantly reduces the attack surface. Furthermore, monitoring for anomalous traffic patterns directed at UDP ports 67 and 68 can help detect exploitation attempts in real-time. Security operations centers should look for unusual packet sizes or malformed DHCP requests that deviate from standard protocol behavior, as these may indicate probing activity related to this vulnerability. Aligning defense-in-depth measures with ATT&CK techniques such as T1046 Network Service Discovery and T1537 Transfer Data to Cloud Account can help in identifying the subsequent actions an attacker might take after successfully exploiting this initial information disclosure flaw.