CVE-2026-83924 in Windows
Summary
by MITRE • 10/14/2026
Use after free in Windows Kernel allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described constitutes a critical security flaw within the Microsoft Windows operating system kernel, specifically categorized as a use-after-free error. This type of memory corruption issue arises when software continues to utilize a pointer that references a previously deallocated or freed block of memory. In the context of the Windows Kernel, which operates at ring 0 with unrestricted access to hardware and system resources, such an error is particularly severe because it compromises the integrity of core operating system functions. The root cause typically involves a race condition or logic error where the kernel fails to properly nullify pointers after freeing associated memory structures, allowing subsequent operations to interact with stale data that may have been reallocated for different purposes by other processes or subsystems.
From an attacker's perspective, this vulnerability presents a direct pathway for local privilege escalation. An authorized user on the system can exploit this flaw by crafting specific inputs or triggering specific kernel routines in a precise sequence designed to manipulate memory allocation patterns. By doing so, the attacker can cause the kernel to execute arbitrary code within its own context rather than that of the unprivileged application. This effectively bypasses standard security boundaries and access control mechanisms, granting the malicious process administrative rights equivalent to those held by the SYSTEM account or other high-privilege entities. The ability to escalate privileges locally is a primary vector for lateral movement in enterprise environments, as it allows an attacker who has gained initial foothold through phishing or web application attacks to gain full control over the compromised host.
The operational impact of this vulnerability extends beyond simple privilege escalation. It undermines the fundamental trust model of the operating system by allowing untrusted code to execute with kernel-level permissions. This can lead to data exfiltration, installation of persistent backdoors, and complete compromise of confidentiality, integrity, and availability for all resources accessible on the machine. Furthermore, because the exploit occurs within the kernel, it is often difficult to detect using standard endpoint detection tools that operate at user mode. The attacker gains a level of stealth and persistence that makes remediation challenging without full system re-imaging or rigorous forensic analysis.
In terms of industry standards, this vulnerability aligns with CWE-416, which defines Use After Free as a software defect where a program uses memory after it has been freed. It also maps to the MITRE ATT&CK framework under techniques related to privilege escalation and defense evasion, specifically those involving kernel exploitation such as T1055 or more specific sub-techniques depending on the exact mechanism of code execution. The exploitability relies heavily on timing and memory layout knowledge, often requiring sophisticated payload construction to achieve reliable code execution without causing a system crash that would alert administrators prematurely.
Mitigation strategies for this class of vulnerability primarily involve applying vendor-provided security patches as soon as they become available. Microsoft typically releases these updates through Windows Update or out-of-band security bulletins when the threat is deemed critical. Organizations should prioritize patching systems where users have administrative privileges, although even standard user accounts can leverage such flaws to gain higher access levels. Additionally, implementing strict application whitelisting and restricting script execution can reduce the attack surface by preventing unauthorized code from running in environments that might trigger the vulnerability. Enabling advanced memory protection features like Kernel Patch Protection (PatchGuard) and Data Execution Prevention (DEP) can also help mitigate some aspects of kernel exploitation, although determined attackers often develop techniques to bypass these controls. Regular auditing of system logs for unusual privilege changes or process injections is recommended to detect potential exploitation attempts post-patch deployment.