CVE-2026-69497 in Windows
Summary
by MITRE • 09/08/2026
Missing release of memory after effective lifetime in Windows DHCP Server allows an authorized attacker to deny service over a network.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability described constitutes a classic resource management error within the Microsoft Dynamic Host Configuration Protocol (DHCP) server component, specifically categorized under CWE-401: Missing Release of Memory after Effective Lifetime. This flaw arises from improper handling of memory allocation and deallocation routines during the processing of specific DHCP message sequences or state transitions. When an authorized attacker interacts with the vulnerable service by sending crafted network packets that trigger this flawed code path, the server fails to properly free allocated memory buffers associated with those requests. Over time, as these leaked allocations accumulate in the system's virtual address space, they consume increasing amounts of physical and virtual memory resources without being returned to the operating system for reuse.
From a technical perspective, the DHCP service operates continuously to manage IP address assignments within a network segment. The vulnerability likely resides in how the server handles dynamic data structures during lease negotiations or renewals where specific edge cases are not correctly processed by the garbage collection or manual memory management routines. Because the attacker is required to be authorized, this implies that valid credentials for the DHCP service or the underlying Windows operating system must be obtained first, which significantly narrows the attack vector but increases the severity of potential impact once access is gained. The lack of proper cleanup leads to a gradual degradation of server performance as available memory dwindles.
The operational impact of this vulnerability is primarily focused on availability rather than confidentiality or integrity. As memory leaks persist, the DHCP server experiences increased latency in responding to client requests and may eventually become unresponsive due to resource exhaustion. This results in a Denial of Service (DoS) condition where legitimate network clients are unable to obtain IP configuration parameters such as subnet masks, default gateways, and DNS server addresses. In critical infrastructure environments relying on automated IP assignment, this disruption can halt business operations, prevent new devices from joining the network, or cause existing connections to drop if leases cannot be renewed effectively.
This behavior aligns with MITRE ATT&CK technique T1499: Endpoint Denial of Service, specifically under sub-techniques involving resource exhaustion through application layer attacks. The attacker leverages their authorized access to systematically exhaust system resources, thereby disrupting the availability of a critical network service. Unlike remote code execution vulnerabilities that compromise data integrity or confidentiality, this flaw targets the reliability and uptime of the DHCP infrastructure, making it particularly dangerous in environments where continuous connectivity is paramount for operational continuity.
Mitigation strategies must address both immediate remediation and long-term architectural resilience. The primary defense involves applying vendor-supplied security patches that correct the memory management logic within the DHCP server binaries to ensure proper deallocation after each request cycle completes. Administrators should also implement network segmentation to restrict access to the DHCP service, ensuring that only trusted subnets can communicate with it, thereby reducing the attack surface even if credentials are compromised. Additionally, deploying monitoring solutions that track memory usage trends for critical services like DHCP can provide early warning signs of resource leaks before they escalate into full-blown denial-of-service events. Regular auditing of authorized access controls and enforcing least-privilege principles further reduces the risk of an attacker gaining the necessary permissions to exploit this flaw in the first place.