6.4.1 Public web application review or automated protection

Public-facing web applications must have new threats and vulnerabilities handled continuously and the applications protected from known attacks using one of two methods. Option one: review the applications, using automated or manual tools or methods for assessing application vulnerability and security, at least every 12 months plus following any significant change, performed by an entity that specialises in application security, covering at minimum every common attack category listed in 6.2.4, with all vulnerabilities ranked per Requirement 6.3.1, all vulnerabilities corrected, and the application re-assessed after correction. Option two: install an automated technical control that constantly spots and stops web-based attacks, placed in front of the public-facing applications, actively running and updated as relevant, producing audit logs, and set either to block attacks or to raise an alert that is investigated immediately. It applies to all entities with public-facing web applications. Applicability: this is distinct from the internal and external scans (11.3.1, 11.3.2); 6.4.2 supersedes this requirement after 31 March 2025, when 6.4.2 becomes effective. Objective under the customized approach: public-facing web applications are defended against malicious attacks.

Source: PCI DSS v4.0.1, 6.4.1. The statement above is our statement of the clause, read from the published text and cited so you can check it against the official text, not the instrument verbatim. Open PCI DSS v4.0.1 in the compliance library.

Version 4.0.1 is the active version; 4.0 has been retired. Appendix A1 applies only to multi-tenant service providers, A2 only to card-present POS POI terminals that still use SSL or early TLS, and A3 only when a payment brand or acquirer requires it. Which requirements apply to you follows your validation type.