CVE-2021-42072: An issue was discovered in Barrier before 2.4.0

Q: How do I fix CVE-2021-42072?

barrier: upgrade to 2.4.0; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-42072 being exploited?

CVE-2021-42072 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-2021-42072 affect?

CVE-2021-42072 affects barrier, fedora. Severity is high (CVSS 8.8). An issue was discovered in Barrier before 2.4.0. The barriers component (aka the server-side implementation of Barrier) does not sufficiently verify the identify of connecting clients. Clients can thus exploit weaknesses in the provided pro

Q: How urgent is CVE-2021-42072?

Priority 55/100. High severity; Public exploit reference

This month

HIGH 8.8UPGRADEMITIGATE

CVE-2021-42072 is a high-severity flaw (CVSS 8.8) affecting barrier, fedora. 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. The barriers component (aka the server-side implementation of Barrier) does not sufficiently verify the identify of connecting clients. Clients can thus exploit weaknesses in the provided protocol to cause denial-of-service or stage further attacks that could lead to information leaks or integrity corruption.

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.7% (top 23%)
CISA exploited list	No
Weakness	CWE-287
Published	2021-11-08
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: barrier project · fedoraproject

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.

fedoraproject fedora MITIGATE

Affected: 34 · 35

Fixed in: no fixed release known

Safe to downgrade to: a release before 34

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2021-42072?

barrier: upgrade to 2.4.0; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-42072 being exploited?

CVE-2021-42072 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-2021-42072 affect?

CVE-2021-42072 affects barrier, fedora. Severity is high (CVSS 8.8). An issue was discovered in Barrier before 2.4.0. The barriers component (aka the server-side implementation of Barrier) does not sufficiently verify the identify of connecting clients. Clients can thus exploit weaknesses in the provided pro

How urgent is CVE-2021-42072?

Priority 55/100. High severity; Public exploit reference

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-2021-42073 HIGH 8.2 UPGRADE An issue was discovered in Barrier before 2.4.0

References

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