CVE-2026-48575

What it actually does

This vulnerability is a local Windows Secure Boot protection mechanism failure that can allow a highly privileged local attacker to bypass a security feature intended to preserve boot-chain integrity. Successful exploitation could undermine trust in the boot process, enabling execution of unauthorized boot components or weakening protections that normally prevent tampering before the operating system fully loads. The CVSS vector indicates local access, low attack complexity, high privileges required, no user interaction, scope change, and high confidentiality and integrity impact, with no direct availability impact.

Why it matters to the business

If exploited, this flaw could let an attacker who already has significant control of a Windows system weaken foundational boot protections, making compromise harder to detect and harder to trust after remediation. The main operational risk is persistence or concealment beneath normal endpoint security controls, especially on workstations and servers that rely on Secure Boot for assurance. It affects many supported Windows client and server versions, including Windows 10, Windows 11, Windows Server 2012, 2016, 2019, 2022, and 2025. Although EPSS is currently low, it should still be prioritized on high-value endpoints, administrator workstations, virtualization hosts, domain infrastructure, and systems subject to compliance requirements for measured or trusted boot.

How an attack unfolds

An attacker must first obtain authorized local access with high privileges on an affected Windows system. From that position, they would attempt to abuse the Secure Boot protection failure to alter or bypass boot-chain enforcement. If successful, the attacker could cause the system to accept boot components or boot configuration states that should normally be blocked, weakening the integrity guarantees provided before Windows and endpoint security tools are fully active. This type of flaw is most valuable after an attacker has already achieved administrative or equivalent control, because it can help preserve access, hide tampering, or defeat assumptions made by disk encryption, endpoint protection, or attestation workflows. No public exploit maturity or known exploited status is currently indicated for this CVE.

How to fix it

Apply the relevant Microsoft security updates for all affected Windows client and server versions as soon as they are available through Windows Update, Microsoft Update Catalog, WSUS, Intune, Configuration Manager, or other enterprise patch tooling. Because no fixed versions were provided in the input, administrators should validate against the latest Microsoft security guidance for this CVE and confirm installation of the applicable cumulative update for each Windows release. Prioritize systems where Secure Boot is a control dependency, including administrator workstations, privileged access workstations, domain controllers, virtualization hosts, servers handling sensitive workloads, and systems using measured boot, device health attestation, BitLocker, or credential-protection features. As mitigation-in-depth, restrict local administrator rights, monitor and control changes to EFI System Partitions and boot configuration, enforce firmware passwords where appropriate, maintain BitLocker recovery governance, and ensure endpoint security tools alert on boot configuration and bootloader changes.

How to confirm the fix worked

Confirm exposure by inventorying Windows build and patch levels across affected versions and comparing them with Microsoft’s security update guidance for this CVE. Verify Secure Boot state using Windows Security, System Information, PowerShell, or enterprise device management reporting. Confirm remediation by ensuring the applicable cumulative update is installed and the system has successfully rebooted after installation. Validate that Secure Boot remains enabled after patching and that boot configuration has not been unexpectedly modified. For representative systems, review event logs for Secure Boot, boot configuration, BitLocker recovery, Code Integrity, and kernel boot events before and after patching to establish a clean baseline. Where available, use endpoint attestation or device health attestation to confirm the expected trusted boot state.

Typical attack path

1. Gain local access to an affected Windows workstation or server.
2. Escalate or use already obtained high-privilege local permissions.
3. Identify whether Secure Boot is enabled and whether the system is running an affected Windows version.
4. Abuse the Secure Boot protection mechanism failure to bypass expected boot-chain enforcement.
5. Modify boot-related components or configuration in a way that would normally be prevented or detected by Secure Boot.
6. Reboot or otherwise trigger the altered boot path.
7. Use the weakened boot trust boundary to maintain persistence, conceal tampering, or bypass security controls that depend on Secure Boot integrity.

How to detect it

To determine whether this was already exploited, focus on evidence of boot-chain tampering rather than network activity, because exploitation is local and requires high privileges. Review Windows Event Logs including System, Security, Microsoft-Windows-Kernel-Boot, Microsoft-Windows-CodeIntegrity/Operational, Microsoft-Windows-BitLocker/BitLocker Management, and DeviceManagement or MDM logs where applicable. Look for unexpected Secure Boot disablement, boot configuration changes, BitLocker recovery events, Code Integrity policy changes, unsigned or unusual boot components, and modifications to the EFI System Partition. Examine EDR telemetry for privileged processes modifying boot configuration or files under the EFI System Partition, especially bcdedit.exe, mountvol.exe, diskpart.exe, powershell.exe, cmd.exe, and firmware or boot management utilities. Correlate suspicious boot-related changes with recent local administrator logons, privilege escalation alerts, endpoint protection tamper events, or unexplained reboots. Because no public exploit artifacts or actor-specific tradecraft are provided, detections should be behavior-based and validated against authorized maintenance activity such as firmware updates, OS upgrades, BitLocker operations, and boot repair procedures.

What your security team should do

• Prioritize patching on high-value Windows systems where boot integrity is critical, including privileged access workstations, domain controllers, virtualization hosts, and sensitive servers.
• Inventory affected Windows 10, Windows 11, and Windows Server versions and track remediation through enterprise patch management until all applicable cumulative updates are installed.
• Treat exploitation risk as post-compromise: combine patching with strong controls over local administrator access, credential hygiene, and privileged session monitoring.
• Audit Secure Boot status and boot configuration across the fleet, especially on systems that recently showed administrator-level compromise indicators or unexpected BitLocker recovery events.
• Monitor for unauthorized changes to the EFI System Partition, bootloaders, boot configuration data, Code Integrity settings, and Secure Boot state.
• Investigate any endpoint where Secure Boot was disabled, boot configuration changed unexpectedly, or BitLocker recovery was triggered without a known maintenance cause.
• Because EPSS is currently low and the CVE is not listed as known exploited, schedule broad fleet remediation through normal emergency/accelerated patch cycles while prioritizing critical assets first.