Advisory Details

August 26th, 2021

Microsoft Windows Canonical Display Driver DrvAlphaBlendInternal Untrusted Pointer Dereference Privilege Escalation Vulnerability

ZDI-21-1014
ZDI-CAN-12871

CVE ID CVE-2021-34516
CVSS SCORE 8.8, (AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H)
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Windows
VULNERABILITY DETAILS

This vulnerability allows local attackers to escalate privileges on affected installations of Microsoft Windows. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the cdd.dll driver. The issue results from the lack of proper validation of a user-supplied value prior to dereferencing it as a pointer. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of SYSTEM.

ADDITIONAL DETAILS Microsoft has issued an update to correct this vulnerability. More details can be found at:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34516
DISCLOSURE TIMELINE
  • 2021-05-13 - Vulnerability reported to vendor
  • 2021-08-26 - Coordinated public release of advisory
CREDIT Marcin Wiazowski
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