Vulnerability identifier: #VU53886

Vulnerability risk: Critical

CVSSv3.1: 9.5 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2021-34527

CWE-ID: CWE-94

Exploitation vector: Network

Exploit availability: Yes

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

Vendor: Microsoft

Description

The vulnerability allows a remote user to execute arbitrary code on the target system.

The vulnerability exists due to improper input validation within the RpcAddPrinterDriverEx() function. A remote user can send a specially crafted request to the Windows Print Spooler and execute arbitrary code with SYSTEM privileges.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Note, the vulnerability is being considered a zero-day and dubbed PrintNightmare. This is a different vulnerability than #VU54508 (CVE-2021-1675).

Mitigation
Install update from vendor's website.

Vulnerable software versions

Windows: 10 - 10 S, 7, 8.1 - 8.1 RT

Windows Server: 2008 - 2019 2004

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External links
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34527

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.