#VU54798 Untrusted Pointer Dereference in Windows and Windows Server - CVE-2021-34516

Vulnerability identifier: #VU54798

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-34516

CWE-ID: CWE-822

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Windows
Operating systems & Components / Operating system
Windows Server
Operating systems & Components / Operating system

Vendor: Microsoft

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to untrusted pointer dereference in DrvTransparentBltInternal() within the Microsoft Windows Canonical Display Driver cdd.dll. A local user can run a specially crafted program to execute arbitrary code with SYSTEM privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Windows: 7, 8.1 RT - 8.1, 10 20H2 10.0.19042.572, 10 21H1 10.0.19043.985, 10 1511 10.0.10586.3, 10 1607 10.0.14393.10, 10 1703 10.0.15063.138, 10 1709 10.0.16299.19, 10 1803 10.0.17134.48, 10 1809 10.0.17763.1, 10 1909 10.0.18363.476, 10 2004 10.0.19041.264, 10

Windows Server: 2008 R2 - 2008, 2012 R2 - 2012, 2016 10.0.14393.10, 2019 10.0.17763.1 - 2019 2004

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External links
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34516
https://www.zerodayinitiative.com/advisories/ZDI-21-895/

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.