CVE-2026-48578: 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 with no network exposure required, and the attacker must already hold a high-privilege account on the target system. Successful exploitation lets the attacker undermine the boot integrity chain, enabling persistent tampering with boot components and full disclosure of protected boot-stage data. Patched-image rebuilds at the applicable fix versions are available on HarborGuard for environments running affected Windows versions.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityNot required

  The attack vector is local (AV:L), so the attacker needs an existing shell or process on the host rather than any network path.

• AuthenticationRequired

  The attacker must hold a high-privilege (administrative) account on the target system before exploitation is possible (PR:H).

• Victim interactionNot required

  No action from another user is needed; the attacker can trigger the bypass entirely on their own (UI:N).

• Attack complexityDetail

  Attack complexity is low (AC:L), meaning the exploit is reliable and does not depend on race conditions, specific memory layouts, or other environmental factors.

Blast Radius

• Reads protected boot-stage secrets and integrity measurements stored in Secure Boot variables, defeating confidentiality guarantees at the firmware layer.
• Modifies boot components such as bootloaders and early-load drivers, allowing persistent implants that survive OS reinstallation.
• Bypasses code-signing enforcement at boot time, permitting unsigned or revoked kernel modules and drivers to load without restriction.