CVE-2026-67402 in Security & Firewall
Summary
by MITRE • 09/04/2026
An insecure Apache configuration in ConfigServer Security & Firewall maps /usr/bin as CGI programs through the Messenger v3 HTTPS virtual host. A remote unauthenticated attacker whose address is blocked can request a mapped executable and run arbitrary commands as the Apache user. The vulnerability affects installations where CSF Messenger v3 and its HTTPS mode are enabled. WebPros addressed the vulnerability in version 16.31.
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Analysis
by VulDB Data Team • 09/04/2026
The security flaw resides within the configuration of ConfigServer Security & Firewall, specifically affecting deployments that have enabled the Messenger v3 feature with HTTPS support active. This misconfiguration results in an insecure mapping where the system directory /usr/bin is exposed as a CGI program handler through the web server interface associated with the Messenger virtual host. By designating this critical binary directory for Common Gateway Interface execution, the application inadvertently allows external requests to target executable files located within that path. The vulnerability stems from improper access control logic and insufficient validation of request origins relative to restricted system directories, creating a pathway for unauthorized code execution.
The operational impact is severe because it grants remote unauthenticated attackers the ability to execute arbitrary commands with the privileges of the Apache web server user. Although the attacker's IP address may be blocked by standard firewall rules within ConfigServer Security & Firewall, this specific vulnerability bypasses those restrictions due to the way the HTTPS virtual host processes requests for mapped CGI resources. This effectively neutralizes a primary layer of defense intended to block malicious traffic, allowing an adversary who can reach the web service interface to run commands on the underlying operating system. The scope of damage is limited by the permissions assigned to the Apache user process; however, depending on how that user is configured and what other services are running under its context, this could lead to full server compromise or lateral movement within a network environment.
From an industry standard perspective, this vulnerability aligns with CWE-94 Improper Control of Generation of Code (Code Injection) as it allows the execution of arbitrary code via web interface manipulation. It also relates closely to CWE-284 Improper Access Control because the configuration fails to restrict access to sensitive system directories based on authentication or authorization status, despite existing firewall rules that should theoretically block such attempts. In terms of MITRE ATT&CK mapping, this scenario reflects techniques associated with Initial Access and Execution, specifically leveraging web applications for command execution when proper input validation and output encoding are not enforced by the application logic itself.
Mitigation strategies must focus on immediate remediation through software updates and configuration hardening. The vendor WebPros addressed this issue in version 16.31 of ConfigServer Security & Firewall; therefore, upgrading to this patched version or later is the primary corrective action required to resolve the underlying code flaw. Administrators should verify that their installations are updated immediately upon availability of the patch. In addition to updating software, organizations should review their web server configurations to ensure that sensitive system directories like /usr/bin are never mapped as CGI handlers unless absolutely necessary and strictly controlled with robust authentication mechanisms. Regular audits of firewall rules and virtual host settings can help prevent similar misconfigurations where security controls intended for network-level protection are undermined by application-layer vulnerabilities.