CVE-2021-42073: An issue was discovered in Barrier before 2.4.0

Q: How do I fix CVE-2021-42073?

barrier: upgrade to 2.4.0. Exact commands for each OS are on this page.

Q: Is CVE-2021-42073 being exploited?

CVE-2021-42073 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-42073 affect?

CVE-2021-42073 affects barrier. Severity is high (CVSS 8.2). An issue was discovered in Barrier before 2.4.0. An attacker can enter an active session state with the barriers component (aka the server-side implementation of Barrier) simply by supplying a client label that identifies a valid client con

Q: How urgent is CVE-2021-42073?

Priority 57/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 8.2REMOTEUPGRADE

CVE-2021-42073 is a high-severity flaw (CVSS 8.2) affecting barrier. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in Barrier before 2.4.0. An attacker can enter an active session state with the barriers component (aka the server-side implementation of Barrier) simply by supplying a client label that identifies a valid client configuration. This label is "Unnamed" by default but could instead be guessed from hostnames or other publicly available information. In the active session state, an attacker can capture input device events from

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 27%)
CISA exploited list	No
Weakness	CWE-384
Published	2021-11-08
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: barrier project

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

Am I affected?

Timeline

2021-11-08 04:15 UTCPublished CVE record published
2026-06-17 04:09 UTCUpdated Record last modified

barrier project barrier UPGRADE

Affected: < 2.4.0

Fixed in: 2.4.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy barrier || rpm -q barrier || barrier --version

2. UPGRADE to 2.4.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade barrier

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade barrier

Note

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

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-2021-42073?

barrier: upgrade to 2.4.0. Exact commands for each OS are on this page.

Is CVE-2021-42073 being exploited?

CVE-2021-42073 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-2021-42073 affect?

CVE-2021-42073 affects barrier. Severity is high (CVSS 8.2). An issue was discovered in Barrier before 2.4.0. An attacker can enter an active session state with the barriers component (aka the server-side implementation of Barrier) simply by supplying a client label that identifies a valid client con

How urgent is CVE-2021-42073?

Priority 57/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-42076 HIGH 7.5 UPGRADE An issue was discovered in Barrier before 2.3.4
CVE-2021-42075 HIGH 7.5 UPGRADE An issue was discovered in Barrier before 2.3.4
CVE-2021-42074 HIGH 7.5 UPGRADE An issue was discovered in Barrier before 2.3.4
CVE-2021-42072 HIGH 8.8 UPGRADE MITIGATE An issue was discovered in Barrier before 2.4.0

References

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