CVE-2026-83634 in Windows
Summary
by MITRE • 10/14/2026
Double free in Windows BitLocker allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as a double free error within the Microsoft Windows BitLocker component represents a critical memory management flaw that can be exploited by authenticated users to achieve local privilege escalation. This type of defect occurs when a program attempts to deallocate or release a block of memory more than once without properly resetting the pointer or verifying its allocation status in between operations. In the context of operating system kernels and security subsystems like BitLocker, such errors are particularly dangerous because they can corrupt internal data structures used by the kernel for managing resources and enforcing access controls. The presence of this flaw indicates a failure in proper memory lifecycle management within the driver code responsible for handling encryption keys or volume metadata during specific administrative operations.
From a technical perspective, double free vulnerabilities often lead to heap corruption, which allows an attacker to manipulate how subsequent memory allocations are handled by the system. By carefully crafting inputs that trigger the erroneous deallocation sequence, an authorized user can overwrite adjacent memory structures with controlled data. This manipulation can alter function pointers or object headers within the kernel space, effectively hijacking the control flow of the operating system. When exploited successfully, this mechanism enables the attacker to execute arbitrary code with SYSTEM-level privileges, bypassing standard security boundaries that normally restrict administrative actions to specific trusted processes.
The operational impact of this vulnerability is severe due to its potential for privilege escalation from a low-privileged or even medium-privileged account to full kernel control. Although BitLocker typically requires authentication and often involves physical access scenarios involving pre-boot authentication, the existence of an authenticated vector means that any user with valid credentials on the system could potentially exploit this flaw if they can trigger the specific code path containing the double free condition. This undermines the integrity guarantees provided by disk encryption solutions, as a compromised local account could extract sensitive data or disable security features entirely after gaining elevated rights.
Industry standards classify this type of vulnerability under CWE-415, which defines Double Free as an error where memory is freed more than once, leading to undefined behavior and potential exploitation. Furthermore, the attack technique aligns with MITRE ATT&CK tactic T1068, specifically subtechnique 1068.002 for Exploitation for Privilege Escalation via kernel exploits or driver vulnerabilities. Mitigation strategies primarily involve applying vendor-provided security patches that address the memory management logic within the BitLocker drivers to ensure proper validation before deallocation and prevent multiple releases of the same resource. Administrators should also enforce strict least-privilege policies to limit the number of users with administrative rights, thereby reducing the attack surface available for triggering such kernel-level exploits until updates are deployed.