CVE-2020-3998: VMware Horizon Client for Windows (5.x prior to 5.5.0) contains an information disclosure vulnerability

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MEDIUM 6.5UPGRADE

CVE-2020-3998 is a medium-severity flaw (CVSS 6.5) affecting horizon client. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

VMware Horizon Client for Windows (5.x prior to 5.5.0) contains an information disclosure vulnerability. A malicious attacker with local privileges on the machine where Horizon Client for Windows is installed may be able to retrieve hashed credentials if the client crashes.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.3% (top 30%)
CISA exploited list	No
Published	2020-10-23
Last modified	2026-06-17

Publisher (CNA): VMware · Vendor: vmware

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-10-23 14:15 UTCPublished CVE record published
2026-06-17 03:19 UTCUpdated Record last modified

vmware horizon client UPGRADE

Affected: >= 5.0.0 and < 5.5.0

Fixed in: 5.5.0

Safe to downgrade to: a release before 5.0.0

1. Check installed version

apt-cache policy horizon-client || rpm -q horizon-client || horizon-client --version

2. UPGRADE to 5.5.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade horizon-client

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade horizon-client

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 5.0.0 (Debian / Ubuntu)

apt-cache madison horizon-client sudo apt install horizon-client=<VERSION_BEFORE_5.0.0> sudo apt-mark hold horizon-client

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list horizon-client sudo dnf downgrade horizon-client-<VERSION_BEFORE_5.0.0> sudo dnf versionlock add horizon-client

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-3998?

horizon client: upgrade to 5.5.0. Exact commands for each OS are on this page.

Is CVE-2020-3998 being exploited?

CVE-2020-3998 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-3998 affect?

CVE-2020-3998 affects horizon client. Severity is medium (CVSS 6.5). VMware Horizon Client for Windows (5.x prior to 5.5.0) contains an information disclosure vulnerability. A malicious attacker with local privileges on the machine where Horizon Client for Windows is installed may be able to retrieve hashed

How urgent is CVE-2020-3998?

Priority 40/100. No elevated risk signals yet.

Software pages

Windows vulnerabilities · VMware vulnerabilities

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References

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