CVE-2021-34498: 
vulnerability analysis and mitigation

Windows GDI Elevation of Privilege Vulnerability (CVE-2021-34498) was discovered and reported to Microsoft on April 27, 2021, with public disclosure occurring on July 19, 2021. The vulnerability affects Microsoft Windows systems and specifically involves the Windows GDI (Graphics Device Interface) component (ZDI Advisory).

The vulnerability exists within the handling of bitmap objects in Windows win32kfull. The specific flaw stems from the lack of validation for object existence prior to performing operations on the object. This vulnerability has been assigned a CVSS score of 8.8 (AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H), indicating its high severity (ZDI Advisory).

If successfully exploited, this vulnerability allows attackers to escalate privileges and execute arbitrary code in the context of SYSTEM, effectively gaining complete control over the affected system (ZDI Advisory).

The vulnerability requires local access and the ability to execute low-privileged code on the target system to be exploited. An attacker must first obtain the ability to run code with low privileges on the target system before attempting to exploit this vulnerability (ZDI Advisory).

Microsoft has released security updates to address this vulnerability. The fixes are available through various KB updates including KB5004237, KB5004238, KB5004244, KB5004245, and KB5004249 for different versions of Windows (Rapid7).