CVE-2026-116638 in Windows
Summary
by MITRE • 10/26/2026
The Windows Recovery Environment (WinRE) in Windows 10 and 11 may allow an attacker to bypass firmware security controls, including administrator-configured UEFI/BIOS passwords. An attacker with physical or administrative access to a device may be able to leverage WinRE-related boot mechanisms to circumvent firmware protections and gain unauthorized access to system resources.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/26/2026
The Windows Recovery Environment (WinRE) presents a significant security risk when it can be leveraged by an adversary to bypass critical firmware-level security controls, specifically administrator-configured Unified Extensible Firmware Interface or Basic Input/Output System passwords. This vulnerability stems from the inherent design of WinRE as a pre-boot environment intended for system repair and recovery operations. While these features are essential for legitimate administrative tasks such as resetting lost credentials or repairing corrupted boot sectors, they can be exploited by attackers who possess physical access to the target device or have obtained local administrator privileges. The core technical flaw lies in the ability of WinRE mechanisms to initiate a boot sequence that operates with elevated trust levels relative to standard user contexts, allowing an attacker to interrupt normal startup procedures and load alternative operating system images or command-line tools that do not respect firmware-level authentication barriers.
From a technical perspective, this vulnerability exploits the interaction between the bootloader, the pre-boot environment, and the hardware initialization process. When WinRE is triggered, typically through specific boot flags or recovery media invocation, it loads into memory before full user-mode security policies are enforced by the operating system kernel. An attacker can utilize tools available within WinRE to access low-level disk structures, modify boot configuration data, or reset local account passwords without requiring the firmware password that would normally prevent such modifications at a lower level of abstraction. This effectively neutralizes one of the primary defenses against physical theft or unauthorized hardware manipulation, as the firmware lock is circumvented by leveraging trusted recovery utilities that are signed and verified by Microsoft but executed in an environment where traditional access controls do not apply to the underlying storage devices.
The operational impact of this vulnerability is severe for organizations relying on device-level encryption and BIOS/UEFI passwords as their primary perimeter defense against physical attacks. If an attacker can boot into WinRE, they may be able to disable BitLocker drive encryption by clearing or bypassing the pre-boot authentication requirements, thereby gaining plaintext access to all data stored on the system drives. Furthermore, the ability to reset local administrator accounts allows for persistent unauthorized access even after initial entry is detected and remediated at the network level. This undermines the principle of defense in depth, as it renders hardware-based security measures ineffective against determined adversaries with physical proximity or compromised administrative credentials. The risk is particularly acute in environments where devices are frequently moved between locations or used by multiple users who may have varying levels of trust and access rights.
To mitigate this vulnerability, organizations must implement a multi-layered approach to endpoint security that does not rely solely on firmware passwords. Enabling Secure Boot ensures that only signed bootloaders can execute during the startup process, reducing the attack surface for unauthorized recovery environments. Additionally, configuring Group Policy settings to disable or restrict access to WinRE and other pre-boot repair tools is critical; this includes disabling the ability to enter recovery mode via standard user interactions and requiring additional authentication factors before allowing entry into advanced boot options. Administrators should also ensure that physical port security measures are in place to prevent the use of external boot media, although software-based restrictions on local recovery mechanisms remain the most effective countermeasure against exploitation by those with administrative access. Regular auditing of BIOS/UEFI settings and monitoring for unauthorized changes to boot configuration data can help detect attempts to exploit this flaw before significant damage occurs.
This vulnerability aligns with CWE-250, which describes execution with unnecessary privileges, as it allows an actor to perform actions that exceed their intended authorization level by exploiting trusted system components. It also maps directly to MITRE ATT&CK technique T1499, Endpoint Denial of Service, in the context of disrupting normal security controls, and more specifically relates to techniques involving bootkit or firmware manipulation such as T1507 if used for persistence after gaining access. The exploitation path often involves initial access through physical means or compromised credentials followed by privilege escalation via system configuration discovery and modification. Security teams must recognize that traditional perimeter defenses are insufficient against threats originating from within the trusted boundary of a device's hardware, necessitating stricter controls over recovery environments and boot processes to maintain integrity and confidentiality of enterprise assets.