Host and event action script regex validation can be bypassed in certain situations, leading to potential command injection (CVE-2026-23920)

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    • Type: Defect (Security)
    • Resolution: Fixed
    • Priority: Major
    • None
    • Affects Version/s: None
    • Component/s: Proxy (P), Server (S)
    • None

      CVE ID CVE-2026-23920
      CVSS score 7.7 (High)
      CVSS vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
      Affected components Server, Proxy
      Summary Host and event action script regex validation can be bypassed in certain situations, leading to potential command injection
      Description 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.
      Known attack vectors Authenticated users with script execution permissions can bypass ^ and $ regex validation by injecting a newline character.
      Affected and fix version/s Affected: 7.0.0 - 7.0.21 → Fixed: 7.0.22
      Affected: 7.2.0 - 7.2.14 → Fixed: 7.2.15
      Affected: 7.4.0 - 7.4.5 → Fixed: 7.4.6
      Mitigation Update the affected components to their respective fixed versions.
      Workarounds It is possible to use \A and \z anchors in the regex validation as a workaround.
      Acknowledgements Zabbix wants to thank YoKo Kho (@YoKoAcc) from PT ITSEC Asia, Tbk for submitting this report on the HackerOne bug bounty platform.

            Assignee:
            Zabbix Support Team
            Reporter:
            Janis Nulle
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              Created:
              Updated:
              Resolved: