CVE-2021-3325: Monitorix 3.13.0 allows remote attackers to bypass Basic Authentication in a default installation (i.e., an in

This week

CRITICAL 9.8REMOTEDOWNGRADEMITIGATE

CVE-2021-3325 is a critical-severity flaw (CVSS 9.8) affecting monitorix, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Monitorix 3.13.0 allows remote attackers to bypass Basic Authentication in a default installation (i.e., an installation without a hosts_deny option). This issue occurred because a new access-control feature was introduced without considering that some exiting installations became unsafe, upon an update to 3.13.0, unless the new feature was immediately configured.

Why this priority

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

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.3% (top 17%)
CISA exploited list	No
Published	2021-01-27
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fedoraproject · fibranet

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

Am I affected?

Timeline

2021-01-27 19:15 UTCPublished CVE record published
2026-06-17 04:04 UTCUpdated Record last modified

fibranet monitorix DOWNGRADE

Affected: 3.13.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.13.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.13.0 (Debian / Ubuntu)

apt-cache madison monitorix sudo apt install monitorix=<VERSION_BEFORE_3.13.0> sudo apt-mark hold monitorix

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list monitorix sudo dnf downgrade monitorix-<VERSION_BEFORE_3.13.0> sudo dnf versionlock add monitorix

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.

fedoraproject fedora MITIGATE

Affected: 32 · 33

Fixed in: no fixed release known

Safe to downgrade to: a release before 32

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-2021-3325?

monitorix: downgrade or apply the listed mitigation; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-3325 being exploited?

CVE-2021-3325 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-2021-3325 affect?

CVE-2021-3325 affects monitorix, fedora. Severity is critical (CVSS 9.8). Monitorix 3.13.0 allows remote attackers to bypass Basic Authentication in a default installation (i.e., an installation without a hosts_deny option). This issue occurred because a new access-control feature was introduced without consideri

How urgent is CVE-2021-3325?

Priority 65/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2018-7649 MEDIUM 6.1 UPGRADE Monitorix before 3.10.1 allows XSS via CGI variables.
CVE-2013-7071 MEDIUM 6.1 UPGRADE Cross-site scripting (XSS) vulnerability in the handle_request function in lib/HTTPServer.pm in Monitorix befo
CVE-2013-7070 CRITICAL 9.8 UPGRADE The handle_request function in lib/HTTPServer.pm in Monitorix before 3.3.1 allows remote attackers to execute

References

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