CVE-2021-31977: Windows Hyper-V Denial of Service Vulnerability

Overview

Severity

High (CVSS 8.6)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C

Category

Denial of Service

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2021-Jun

Released

2021-06-08

EPSS Score

6.08% (percentile: 90.8%)

FAQ

How might an attacker attempt to exploit this vulnerability? By sending a specially crafted message to the Hyper-V host virtualization stack, a guest VM could cause a reference count in the host virtualization stack to be leaked. In most circumstances, this would result in a memory leak on the Hyper-V host. If the leaked reference count value were to overflow, reference count hardening built-in to the Hyper-V virtualization stack would cause the host to bugcheck (crash) in a controlled manner, mitigating this issue against exploitation for code execution or privilege elevation.

Affected Products (12)

Windows

• Windows 10 Version 1809 for x64-based Systems
• Windows Server 2019
• Windows Server 2019 (Server Core installation)
• Windows 10 Version 1909 for x64-based Systems
• Windows 10 Version 21H1 for x64-based Systems
• Windows 10 Version 2004 for x64-based Systems
• Windows Server, version 2004 (Server Core installation)
• Windows Server, version 20H2 (Server Core Installation)
• Windows 10 for x64-based Systems
• Windows 10 Version 1607 for x64-based Systems
• Windows Server 2016
• Windows Server 2016 (Server Core installation)

Security Updates (5)

• 5003646
• 5003635
• 5003637
• 5003687
• 5003638

Revision History

• 2021-06-08: Information published.