How severe is CVE-2020-3991?

CVE-2020-3991 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2020-3991 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-3991?

CVE-2020-3991 affects Vmware Horizon Client. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-3991?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-3991 published?

CVE-2020-3991 was published on 2020-10-16 and last updated on 2026-06-17.

CVE-2020-3991

CVE-2020-3991 is a high-severity vulnerability in Vmware Horizon Client with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.1)
CVSS v2: 3.6
EPSS exploit prediction: 0% (26th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Vmware Horizon Client
Published: 2020-10-16
Last modified: 2026-06-17

Description

VMware Horizon Client for Windows (5.x before 5.5.0) contains a denial-of-service vulnerability due to a file system access control issue during install time. 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.

Frequently asked questions

What is CVE-2020-3991?: VMware Horizon Client for Windows (5.x before 5.5.0) contains a denial-of-service vulnerability due to a file system access control issue during install time. 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.
How severe is CVE-2020-3991?: CVE-2020-3991 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2020-3991 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-3991?: CVE-2020-3991 affects Vmware Horizon Client. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-3991?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-3991 published?: CVE-2020-3991 was published on 2020-10-16 and last updated on 2026-06-17.

References

https://www.vmware.com/security/advisories/VMSA-2020-0022.html

Affected products (1)

cpe:2.3:a:vmware:horizon_client:*:*:*:*:*:*:*:*

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