CVE-2026-48568: Secure Boot Security Feature Bypass Vulnerability

Synopsis

A protection mechanism failure in Windows Secure Boot allows an attacker who already holds administrative privileges on a local machine to bypass the Secure Boot security feature entirely. The vulnerability is exploited locally and requires no network access or victim interaction, though it does require an account with high privileges. Successful exploitation lets an attacker load unsigned or untrusted boot components, undermining the chain of trust from firmware through the operating system loader. A patched-image rebuild at the fix versions is 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 path to the target is required.

• AuthenticationRequired

  An administrator or other high-privilege account is needed to exploit this vulnerability; standard unprivileged accounts are not sufficient.

• Victim interactionNot required

  No action from another user or victim is required; the attacker operates entirely on their own session.

• Attack complexityDetail

  Attack complexity is low, meaning the exploit is reliable and does not depend on race conditions, specific memory layout, or other variable environmental factors.

Blast Radius

• An attacker loads unsigned or otherwise untrusted boot components, bypassing Secure Boot enforcement and breaking the firmware-to-OS chain of trust.
• Confidential data protected by boot-time integrity checks (such as BitLocker keys derived from TPM measurements) becomes readable to the attacker.
• Persistent, low-level implants or bootkits can be installed that survive OS reinstallation and are invisible to OS-level security tooling.
• Because the scope is Changed (S:C in the CVSS vector), the compromise extends beyond the initially vulnerable component and can affect the broader system trust boundary.