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Microsoft Windows win32kfull MulLineTo Untrusted Pointer Dereference Privilege Escalation Vulnerability

April 29th, 2021

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 win32kfull.sys 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-2021-27077

Disclosure Timeline

  • 2020-12-23 - Vulnerability reported to vendor
  • 2021-04-29 - Coordinated public release of advisory

Credit

Marcin Wiazowski

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