CVE-2026-23920 Zabbix CVE debrief

Who should care

System administrators and security teams responsible for Zabbix installations should verify and restrict user input validation, implement proper regex patterns, and monitor for suspicious activity related to shell command injection. They should review and update their security controls to prevent similar vulnerabilities in the future. Additionally, they should ensure that user input validation is properly configured and that regex patterns are correctly-im

Why it matters

Authenticated users can inject shell commands due to regex validation bypass in Zabbix installations. System administrators and security teams should verify and restrict user input validation, implement proper regex patterns, and monitor for suspicious activity.

• Verify and restrict user input validation to prevent command injection
• Implement proper regex patterns to avoid similar bypasses
• Monitor for suspicious activity related to shell command injection

Technical summary

The vulnerability allows authenticated users to inject shell commands by bypassing regex validation checks in Zabbix installations. The issue arises from the use of ^ and $ anchors in user input validation, which can be bypassed by injecting newline characters. This allows attackers to execute arbitrary shell commands. The vulnerability affects Zabbix installations where user input is validated with a regex set by the administrator, and the validation runs in multiline mode. Technical details indicate that the regex validation issue can be exploited by authenticated users to inject shell commands.

Defensive priority

Verify and restrict user input validation.

Recommended defensive actions

• Verify and restrict user input validation to prevent command injection
• Implement proper regex patterns to avoid similar bypasses
• Monitor for suspicious activity related to shell command injection
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

CVE and NVD records indicate a regex validation issue in Zabbix installations. The vulnerability allows authenticated users to inject shell commands by bypassing regex validation checks. Evidence from CVE and NVD records suggests that the issue is related to the use of ^ and $ anchors in user input validation, which can be bypassed by injecting newline characters. Defenders should verify Zabbix installations and user input validation to prevent command injection.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.