CVE-2026-23920: Host and event action script input is validated with a regex (set by the administrator), but the validation ru

Routine

HIGH 8.8UPGRADE

CVE-2026-23920 is a high-severity flaw (CVSS 8.8) affecting zabbix. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Host and event action script input is validated with a regex (set by the administrator), but the validation runs in multiline mode. If ^ and $ anchors are used in user input validation, an injected newline lets authenticated users bypass the check and inject shell commands.

Why this priority

High severity

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	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-78
Published	2026-03-24
Last modified	2026-09-10

Publisher (CNA): Zabbix · Vendor: zabbix

Last updated 2026-09-10 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-24 19:16 UTCPublished CVE record published
2026-09-10 21:15 UTCUpdated Record last modified

zabbix zabbix UPGRADE

Affected: >= 7.0.0 and < 7.0.22 · >= 7.2.0 and < 7.2.15 · >= 7.4.0 and < 7.4.6

Fixed in: 7.0.22, 7.2.15, 7.4.6

Safe to downgrade to: a release before 7.0.0

1. Check installed version

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

2. UPGRADE to 7.0.22 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade zabbix

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 zabbix sudo apt install zabbix=<VERSION_BEFORE_7.0.0> sudo apt-mark hold zabbix

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

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

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-2026-23920?

zabbix: upgrade to 7.0.22, 7.2.15, 7.4.6. Exact commands for each OS are on this page.

Is CVE-2026-23920 being exploited?

CVE-2026-23920 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-2026-23920 affect?

CVE-2026-23920 affects zabbix. Severity is high (CVSS 8.8). Host and event action script input is validated with a regex (set by the administrator), but the validation runs in multiline mode. If ^ and $ anchors are used in user input validation, an injected newline lets authenticated users bypass th

How urgent is CVE-2026-23920?

Priority 37/100. High severity

Software pages

Zabbix vulnerabilities

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References

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