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AUSCERT External Security Bulletin Redistribution
VMSA-2020-0022 - VMware Horizon Client update addresses a
denial-of-service vulnerability (CVE-2020-3991)
19 October 2020
AusCERT Security Bulletin Summary
Product: VMware Horizon Client for Windows
Operating System: VMware ESX Server
Impact/Access: Overwrite Arbitrary Files -- Existing Account
Denial of Service -- Existing Account
CVE Names: CVE-2020-3991
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Advisory ID: VMSA-2020-0022
CVSSv3 Range: 5.9
Issue Date: 2020-10-15
Updated On: 2020-10-15 (Initial Advisory)
Synopsis: VMware Horizon Client update addresses a denial-of-service
1. Impacted Products
o VMware Horizon Client for Windows
A denial-of-service vulnerability affecting VMware Horizon Client for
Windows was privately reported to VMware. Updates are available to address this
vulnerability in affected VMware product.
3. File system access control denial-of-service vulnerability (CVE-2020-3991)
VMware Horizon Client for Windows contains a denial-of-service vulnerability
due to a file system access control issue during install time. VMware has
evaluated the severity of this issue to be in the Moderate severity range with
a maximum CVSSv3 base score of 5.9.
Known Attack Vectors
Successful exploitation of this issue may allow an attacker to overwrite
certain admin privileged files through a symbolic link attack at install time.
This will result into a denial-of-service condition on the machine where
Horizon Client for Windows is installed.
To remediate CVE-2020-3991 apply the patches listed in the 'Fixed Version'
column of the 'Response Matrix' below.
VMware would like to thank Eran Shimony of CyberArk for reporting this issue to
Product Version Running CVE CVSSv3 Severity Fixed Workarounds Additional
On Identifier Version Documentation
Client 5.x and Windows CVE-2020-3991 5.9 moderate 5.5.0 None None
Fixed Version(s) and Release Notes:
Horizon Client for Windows 5.5.0
Downloads and Documentation:
Mitre CVE Dictionary Links:
FIRST CVSSv3 Calculator:
5. Change Log
Initial security advisory.
E-mail list for product security notifications and announcements:
This Security Advisory is posted to the following lists:
PGP key at:
VMware Security Advisories
VMware Security Response Policy
VMware Lifecycle Support Phases
VMware Security & Compliance Blog
Copyright 2020 VMware Inc. All rights reserved.
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