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CVE-2026-67402 – Unauthenticated Remote Code Execution – ConfigServer Security & Firewall (CSF) 14.0

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Summary

CVE-2026-67402 is a critical remote code execution vulnerability in ConfigServer Security & Firewall (CSF) caused by an insecure Apache configuration that exposes /usr/bin as CGI programs through the Messenger v3 HTTPS virtual host. The flaw allows a remote, unauthenticated attacker — including one whose IP address is already blocked by CSF — to request mapped system binaries and execute arbitrary commands as the Apache user. It carries a CVSS score of 9.2 (Critical) and is tracked as CWE-552 (Files or Directories Accessible to External Parties).

Technical details

  • Root cause: CSF’s Messenger v3 HTTPS virtual host configures Apache to map the /usr/bin directory as a CGI-executable directory.
  • Trigger conditions: Messenger v3 must be enabled with its HTTPS mode active; this exposes the mapped binaries to any network client.
  • Attack vector: Network — no authentication or user interaction is required, and CSF’s own IP-blocking protections do not prevent exploitation.
  • Impact: Arbitrary command execution as the Apache user, resulting in loss of confidentiality, integrity, and availability of the affected host.

Affected software

  • WebPros/ConfigServer Security & Firewall (CSF) versions 14.02 through 16.30
  • Fixed in CSF version 16.31

Severity

  • CVSS v4.0 Base Score: 9.2 (Critical)
  • Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:N

Mitigation and recommended actions

  • Immediate: Upgrade ConfigServer Security & Firewall to version 16.31 or later.
  • If patching is not immediately possible: Disable Messenger v3 by setting MESSENGERV3 = "0" in the CSF configuration until the upgrade to 16.31 can be completed. This is the default configuration for new installations.

How IONIX identifies potentially affected assets

IONIX matches the following signal against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Raw response body: The firewall on this server is blocking your connection.

References

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How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

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  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
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