CVE-2020-3977: VMware Horizon DaaS (7.x and 8.x before 8.0.1 Update 1) contains a broken authentication vulnerability due to

Routine

MEDIUM 6.5UPGRADE

CVE-2020-3977 is a medium-severity flaw (CVSS 6.5) affecting horizon daas. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

VMware Horizon DaaS (7.x and 8.x before 8.0.1 Update 1) contains a broken authentication vulnerability due to a flaw in the way it handled the first factor authentication. Successful exploitation of this issue may allow an attacker to bypass two-factor authentication process. In order to exploit this issue, an attacker must have a legitimate account on Horizon DaaS.

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	1.0% (top 39%)
CISA exploited list	No
Weakness	CWE-306
Published	2020-09-22
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

2020-09-22 14:15 UTCPublished CVE record published
2026-06-17 03:19 UTCUpdated Record last modified

vmware horizon daas UPGRADE

Affected: >= 8.0.0 and <= 8.0.1 · 7.0.0

Fixed in: newer than 8.0.1

Safe to downgrade to: a release before 7.0.0

1. Check installed version

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

2. UPGRADE to newer than 8.0.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade horizon-daas

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 7.0.0 (Debian / Ubuntu)

apt-cache madison horizon-daas sudo apt install horizon-daas=<VERSION_BEFORE_7.0.0> sudo apt-mark hold horizon-daas

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

dnf --showduplicates list horizon-daas sudo dnf downgrade horizon-daas-<VERSION_BEFORE_7.0.0> sudo dnf versionlock add horizon-daas

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-2020-3977?

horizon daas: upgrade to newer than 8.0.1. Exact commands for each OS are on this page.

Is CVE-2020-3977 being exploited?

CVE-2020-3977 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-2020-3977 affect?

CVE-2020-3977 affects horizon daas. Severity is medium (CVSS 6.5). VMware Horizon DaaS (7.x and 8.x before 8.0.1 Update 1) contains a broken authentication vulnerability due to a flaw in the way it handled the first factor authentication. Successful exploitation of this issue may allow an attacker to bypas

How urgent is CVE-2020-3977?

Priority 38/100. No elevated risk signals yet.

Software pages

VMware vulnerabilities

Related CVEs

CVE-2019-5544 CRITICAL 9.8 EXPLOITED UPGRADE MITIGATE VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow Vulnerability
CVE-2018-6960 HIGH 8.8 UPGRADE VMware Horizon DaaS (7.x before 8.0.0) contains a broken authentication vulnerability that may allow an attack
CVE-2017-4897 MEDIUM 5.5 UPGRADE VMware Horizon DaaS before 7.0.0 contains a vulnerability that exists due to insufficient validation of data

References

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