Section 524B Cybersecurity Documentation: What FDA Expects in Your Premarket Submission

Section 524B Is Not Optional — And FDA Is Paying Attention

If you are preparing a 510(k), De Novo, or PMA submission for a device that contains software or is network-enabled, cybersecurity documentation is no longer a recommendation. Under Section 524B of the Federal Food, Drug, and Cosmetic Act — enacted through the Consolidated Appropriations Act of 2023 — FDA has explicit statutory authority to refuse acceptance of premarket submissions that fail to include adequate cybersecurity information.

That refusal-to-accept authority went into effect on October 1, 2023. Since then, FDA has been clear: submissions that arrive without a coherent, complete cybersecurity package face rejection before substantive review even begins. For a startup burning runway or a mid-size company managing a product pipeline, a Refuse to Accept (RTA) letter is an expensive problem that is entirely avoidable.

This post breaks down exactly what FDA expects, which guidance documents govern the requirements, and how to structure your documentation to pass muster the first time.

The Governing Framework: What You Need to Read

Section 524B itself establishes the statutory mandate, but the operational detail lives in FDA guidance. The primary reference is FDA's final guidance, 'Cybersecurity in Medical Devices: Quality System Considerations and Content of Premarket Submissions', finalized in September 2023. This document supersedes the 2014 and 2022 draft guidances and is the current controlling standard.

Complementary reading includes:

• FDA's 'Postmarket Management of Cybersecurity in Medical Devices' guidance (2016), which informs how your premarket design decisions are evaluated for lifecycle sustainability
• NIST SP 800-30 and SP 800-53, referenced throughout FDA guidance for risk assessment methodology
• IEC 62443 series, particularly relevant for networked device architectures
• AAMI TIR57, which provides a cybersecurity risk management framework recognized by FDA

Understanding where these documents intersect is essential. FDA does not evaluate cybersecurity in isolation — reviewers look for coherence across your risk management file, software documentation, and the cybersecurity submission package itself.

What FDA Actually Wants in Your Submission

1. A Cybersecurity Management Plan

FDA expects a documented plan demonstrating that your organization will manage cybersecurity risks across the total product lifecycle (TPLC). This is not a one-page policy statement. Reviewers want to see defined processes for vulnerability monitoring, coordinated disclosure, patch deployment, and end-of-life planning. If your plan does not address how you will respond after clearance, it is incomplete.

2. Threat Modeling and Risk Assessment

Your submission must include a structured threat model — typically developed using methodologies such as STRIDE or PASTA — that identifies assets, threat actors, attack vectors, and potential impacts. This feeds directly into your cybersecurity risk assessment, which should align with your ISO 14971 risk management process. FDA expects to see residual risk justification, not just a list of identified threats.

3. A Software Bill of Materials (SBOM)

Section 524B explicitly requires an SBOM. This machine-readable inventory must capture all software components — including third-party libraries, open-source packages, and off-the-shelf software — along with version information. The SBOM is the foundation for post-market vulnerability monitoring. If your development team has not implemented an automated SBOM generation process, that gap needs to close before submission.

4. Security Architecture Documentation

FDA reviewers need to understand your device's attack surface. This means documented network diagrams, data flow diagrams, interface descriptions, and a clear accounting of security controls at each layer — authentication, encryption, audit logging, and session management at minimum. For devices interfacing with hospital networks or cloud infrastructure, expect scrutiny on how your architecture handles untrusted environments.

5. Evidence of Security Testing

Penetration testing results, vulnerability scanning reports, and fuzz testing outputs are expected for devices with significant cybersecurity risk. FDA guidance does not prescribe a specific testing methodology, but your testing approach should be commensurate with the device's risk profile and connectivity. Document your testing scope, tools, findings, and remediation actions — and include any residual vulnerabilities with your rationale for acceptance.

Common Mistakes That Trigger RTA or Deficiency Letters

• Submitting a generic cybersecurity policy rather than device-specific documentation
• Omitting third-party or open-source components from the SBOM
• Failing to align cybersecurity risk assessment outputs with the 14971 risk management file
• Providing penetration testing results without remediation documentation
• No postmarket vulnerability disclosure or patch management process defined

Structuring Your Submission for Review Efficiency

FDA's September 2023 guidance recommends organizing cybersecurity documentation as a dedicated section within your submission — not scattered across the software documentation, risk files, and labeling sections. A standalone cybersecurity section with a clear table of contents, cross-references to supporting documents, and an executive summary of your security posture gives reviewers what they need without forcing them to reconstruct your argument from fragments.

Labeling also matters. Section 524B requires that cybersecurity information provided to users — instructions for secure configuration, supported software environments, and known vulnerabilities — appear in device labeling. This is often missed by teams focused entirely on the technical documentation.

The Bottom Line

Section 524B raised the floor on what FDA will accept. The good news is that the requirements are well-defined, the guidance is specific, and a well-prepared submission can move through review without cybersecurity-related deficiencies. The challenge for most teams is that building compliant cybersecurity documentation requires regulatory expertise, engineering depth, and familiarity with how FDA reviewers actually read these packages.

At ADB Consulting and CRO Inc., we work directly with medical device startups and regulatory affairs teams to build submission-ready cybersecurity packages that satisfy Section 524B requirements from the ground up. We have reviewed the guidance, we know what triggers deficiency letters, and we know how to structure your documentation for first-cycle approval.

Book a free discovery call with Andre Butler today at adbccro.com and find out exactly what your submission needs — before FDA tells you what it is missing.