CVE-2026-23923: An unauthenticated attacker can exploit the Frontend 'validate' action to blindly instantiate arbitrary PHP cl

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-23923 is a medium-severity flaw (CVSS 5.3) affecting zabbix. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An unauthenticated attacker can exploit the Frontend 'validate' action to blindly instantiate arbitrary PHP classes. The impact depends on environment setup but appears limited at this time.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 80%)
CISA exploited list	No
Weakness	CWE-470
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 21:16 UTCUpdated Record last modified

zabbix zabbix UPGRADE

Affected: >= 7.4.0 and < 7.4.7

Fixed in: 7.4.7

Safe to downgrade to: a release before 7.4.0

1. Check installed version

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

2. UPGRADE to 7.4.7 (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 7.4.0 (Debian / Ubuntu)

apt-cache madison zabbix sudo apt install zabbix=<VERSION_BEFORE_7.4.0> 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_7.4.0> 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-2026-23923?

zabbix: upgrade to 7.4.7. Exact commands for each OS are on this page.

Is CVE-2026-23923 being exploited?

CVE-2026-23923 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-2026-23923 affect?

CVE-2026-23923 affects zabbix. Severity is medium (CVSS 5.3). An unauthenticated attacker can exploit the Frontend 'validate' action to blindly instantiate arbitrary PHP classes. The impact depends on environment setup but appears limited at this time.

How urgent is CVE-2026-23923?

Priority 29/100. Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities · Zabbix vulnerabilities

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References

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