CVE-2021-26892: 
vulnerability analysis and mitigation

CVE-2021-26892 is a Windows Extensible Firmware Interface Security Feature Bypass Vulnerability that was discovered and reported to Microsoft on December 9, 2020. The vulnerability affects various versions of Microsoft Windows, including Windows 10 and Windows Server 2016 installations (ZDI Advisory).

The vulnerability exists within the Windows kernel and stems from improper authorization logic when accessing files in the EFI partition. The vulnerability has been assigned a CVSS v3.1 base score of 5.5 (Medium) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating local access requirements and potential high impact on system availability (NVD).

When successfully exploited, this vulnerability allows attackers to create a denial-of-service condition on the affected system, potentially impacting system availability (ZDI Advisory).

The vulnerability requires local access to exploit, and an attacker must first obtain the ability to execute low-privileged code on the target system. This requirement somewhat limits the potential for widespread exploitation (ZDI Advisory).

Microsoft has released a security update to address this vulnerability. Users are advised to apply the available patches through the Microsoft security update system (ZDI Advisory).