CVE-2026-69930 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 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 crashes, but rather the unauthorized disclosure of sensitive information residing in adjacent memory regions. An attacker who can interact with the DHCP service over the network can exploit this flaw to leak internal data structures, potentially revealing cryptographic keys, session tokens, or other confidential details that were never intended for external exposure.
From a technical perspective, this vulnerability falls under the category of improper input validation and boundary checking within the application logic handling incoming DHCP requests. The DHCP server must parse variable-length fields in protocol messages, and if the code fails to correctly calculate buffer sizes or validate packet lengths before copying data into fixed-size buffers, it may read past the allocated memory space. This type of error is commonly associated with CWE-125, which defines out-of-bounds read vulnerabilities where software reads data outside of intended boundaries. The impact of such a flaw extends beyond simple information leakage; in some contexts, leaked memory contents can facilitate further attacks by providing attackers with insights into the internal state of the system or other running processes sharing the same address space.
The operational impact is significant because it allows an unauthorized attacker to perform remote information disclosure without requiring authentication on many default configurations. This aligns with ATT&CK technique T1005, which covers Data from Local System, specifically under sub-techniques related to application data or memory dumps obtained through exploitation of software vulnerabilities. The ability to extract sensitive data remotely makes this a high-severity issue for organizations relying on DHCP services for network infrastructure management. Attackers can leverage the leaked information to map internal networks, identify active directory structures, or gather credentials that could lead to more severe compromises such as privilege escalation or lateral movement within the enterprise environment.
Mitigation strategies primarily involve applying the security updates provided by Microsoft to patch the underlying memory handling logic in the DHCP server service. Administrators should ensure that all Windows servers running the DHCP role are updated with the latest cumulative patches addressing this specific vulnerability. Additionally, network segmentation and firewall rules can be employed to restrict access to the DHCP service ports from untrusted networks or unauthorized hosts, thereby reducing the attack surface available to potential exploiters. Monitoring for unusual traffic patterns directed at DHCP services may also help in detecting attempted exploitation activities before significant data exfiltration occurs.