CVE-2026-83842 in Windows
Summary
by MITRE • 10/14/2026
Double free in Windows TCP/IP allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a critical memory management error within the Transmission Control Protocol/Internet Protocol (TCP/IP) stack of Microsoft Windows operating systems, specifically classified as a double-free condition. This flaw arises when the system incorrectly handles deallocation of memory resources associated with network packet processing or connection state maintenance. In standard programming logic, freeing an already freed block of memory leads to undefined behavior, often resulting in heap corruption. For an attacker who has authenticated access to the local machine, this specific implementation error provides a reliable mechanism to manipulate internal kernel data structures and control flow execution paths during the handling of network traffic or TCP/IP state transitions.
From a technical perspective, double-free vulnerabilities are categorized under CWE-415, which denotes Double Free errors that can lead to arbitrary code execution if exploited correctly. The attacker leverages this flaw by triggering specific sequences of network operations that cause the kernel to release a memory pointer twice. This action corrupts the heap metadata or overwrites adjacent data structures with controlled values. By carefully crafting these inputs, the malicious actor can redirect program execution to shellcode injected into the process space or hijack function pointers within the kernel mode driver responsible for TCP/IP processing. Because this occurs in kernel mode, successful exploitation grants the attacker full control over the operating system's security boundary.
The operational impact of exploiting this vulnerability is severe, as it facilitates local privilege escalation from a standard user account to SYSTEM-level privileges. Once an attacker achieves SYSTEM status, they possess unrestricted access to all files on the computer, can install programs, view, change, or delete data, and create new accounts with full administrative rights. This effectively compromises the integrity, confidentiality, and availability of the entire system. The vulnerability is particularly dangerous because it does not require remote code execution capabilities; instead, it relies solely on local authentication, making it a significant threat in environments where users may have legitimate but limited access to workstations or servers that are connected to untrusted networks.
In terms of industry frameworks, this type of exploitation aligns with MITRE ATT&CK technique T1068, which covers Exploitation for Privilege Escalation. Attackers typically use this vulnerability as part of a post-exploitation phase after gaining initial foothold through phishing or other entry points. The double-free mechanism serves as the pivot point that allows moving from low-privilege user context to high-privilege kernel context, bypassing standard access control mechanisms designed to protect sensitive system resources.
Mitigation strategies primarily involve applying vendor-provided security patches that address the memory management logic within the TCP/IP stack. Organizations should prioritize updating all Windows systems with the latest cumulative updates released by Microsoft to close this specific gap. Additionally, implementing strict application whitelisting and least-privilege policies can limit the potential impact if an attacker gains initial access. Network segmentation also plays a role in reducing exposure, although since this is a local privilege escalation flaw, network controls alone are insufficient without proper host-based security measures such as endpoint detection and response solutions that monitor for anomalous memory manipulation patterns indicative of heap exploitation attempts.