CVE-2026-88171 in Windows
Summary
by MITRE • 10/14/2026
Double free in Windows DHCP Server allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as a double free condition within the Microsoft Dynamic Host Configuration Protocol (DHCP) server service represents a critical memory management error that can be exploited by remote, unauthenticated attackers. This flaw resides in how the DHCP Server component handles specific packet structures during its processing routine. When an attacker sends specially crafted network packets to the vulnerable system, they can trigger a sequence of events where the same block of heap memory is freed more than once. In standard programming practices, freeing allocated memory marks it as available for reuse by subsequent allocation requests. However, if that same pointer is used again after being released without proper re-initialization or checks, the application attempts to deallocate already-freed resources. This specific type of error falls under Common Weakness Enumeration category CWE-415, which describes Double Free vulnerabilities where a program frees memory twice, leading to undefined behavior and potential system compromise.
The operational impact of this vulnerability is severe because it allows for arbitrary code execution with the privileges of the DHCP Server service account. Since the DHCP server typically runs under high-level system accounts such as Local System or Network Service on Windows operating systems, successful exploitation grants an attacker full control over the affected machine. This level of access enables the adversary to install programs, view, change, or delete data, and create new accounts with full user rights. Furthermore, because the vulnerability is triggered via network packets, it can be exploited remotely without requiring any prior authentication on the target system. An attacker positioned within the same network segment or capable of routing traffic to the DHCP server port (UDP 67) can initiate this attack vector directly over the network interface.
From a tactical perspective aligned with the MITRE ATT&CK framework, this vulnerability facilitates initial access and privilege escalation techniques often categorized under exploitation for client execution or remote code execution via memory corruption. The double free condition typically leads to heap corruption, which attackers leverage by manipulating the heap metadata to redirect control flow. By carefully crafting the payload that follows the corrupted allocation request, an attacker can overwrite function pointers or exception handlers within the process address space. This mechanism allows them to execute shellcode in the context of the vulnerable service, effectively bypassing many standard security controls that rely on authentication boundaries since no valid credentials are required for exploitation.
Mitigation strategies must focus primarily on applying vendor-supplied patches as soon as they become available from Microsoft Security Updates. Organizations should prioritize systems running the DHCP Server role and ensure that all relevant hotfixes are deployed to address this memory corruption flaw. In environments where immediate patching is not feasible, network segmentation can provide a temporary layer of defense by restricting access to UDP port 67 only from trusted subnets or specific client ranges. Additionally, deploying intrusion detection systems configured with signatures for DHCP packet anomalies may help in identifying and blocking attempts to exploit this vulnerability before they reach the application logic. Regular auditing of system logs for unusual DHCP activity can also aid in early detection of exploitation attempts.