CVE-2026-48570: Secure Boot Security Feature Bypass Vulnerability

Synopsis

A protection mechanism failure in Windows Secure Boot allows a local attacker with administrative privileges to bypass the Secure Boot security feature entirely. The vulnerability is exploited locally and requires no network access, but the attacker must already hold a high-privilege account on the target system. Successful exploitation lets the attacker load unsigned or malicious boot-level code, undermining the chain of trust that Secure Boot is designed to enforce. Patched-image rebuilds at the available fix versions are available on HarborGuard for environments running affected Windows versions.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityNot required

  The attacker needs an existing shell or process on the host; no network access to the target is required.

• AuthenticationRequired

  An admin or otherwise privileged account on the local system is needed to trigger the bypass.

• Victim interactionNot required

  No victim action such as opening a file or clicking a link is required; the attacker operates entirely on their own.

• Attack complexityDetail

  Attack complexity is low, meaning the exploit is reliable and imposes no special preconditions such as race conditions or memory-layout requirements.

Blast Radius

• The attacker disables Secure Boot enforcement, allowing unsigned or attacker-controlled bootloaders and drivers to execute before the OS loads.
• Boot-level persistence mechanisms such as bootkits become installable, surviving OS reinstalls and standard endpoint-detection scans.
• High confidentiality impact means the attacker can read protected boot-level secrets and credentials stored in hardware-backed enclaves or TPM-sealed storage.
• High integrity impact means the attacker can tamper with the boot chain, injecting arbitrary code that runs with full pre-OS privileges on every subsequent system start.