UL 1998-3rd A1: TLS 1.3 & Firmware Audit for V2G Devices

On April 28, 2026, UL Solutions released Supplement A1 to the third edition of UL 1998, mandating TLS 1.3 protocol stack integration and firmware source-code security audit reporting for all vehicle-to-grid (V2G) equipment targeting the U.S. market — effective June 1, 2026. This update directly impacts Chinese manufacturers of V2G communication modules, bidirectional EV chargers, and grid-interfacing controllers exporting to the United States.

Event Overview

UL Solutions officially published Supplement A1 to UL 1998-3rd on April 28, 2026. The supplement requires that, starting June 1, 2026, all V2G devices submitted for UL certification in the U.S. must embed a compliant TLS 1.3 protocol stack and concurrently submit a firmware source-code security audit report issued by a UL-recognized laboratory. The audit must cover 12 defined areas, including memory protection, cryptographic key management, and OTA firmware signature verification.

Industries Affected

Direct Exporters of V2G Hardware

Companies exporting V2G communication modules, bidirectional AC/DC converters, or grid-synchronization controllers to the U.S. will face immediate compliance requirements. Certification submissions after June 1, 2026 must include both TLS 1.3 implementation evidence and the formal audit report — meaning legacy designs without integrated TLS 1.3 stacks may require hardware or firmware rework before submission.

OEMs Integrating V2G Components

Electric vehicle OEMs and energy storage system integrators sourcing V2G-capable controllers from third-party suppliers must now verify upstream compliance. Absence of certified TLS 1.3 support or audited firmware may delay system-level UL listing, as component-level nonconformance cascades to final product evaluation.

Firmware Development & Security Service Providers

Vendors offering secure boot, OTA update frameworks, or cryptographic module integration services will see increased demand for TLS 1.3–compatible implementations and audit-readiness support. The 12-point scope (e.g., key lifecycle handling, runtime memory integrity checks) implies tighter alignment between development practices and UL’s security expectations — not just functional correctness.

Key Considerations and Recommended Actions

Monitor official UL guidance on audit report format and lab recognition

While the requirement is confirmed, UL has not yet published detailed templates for the firmware security audit report or an updated list of recognized labs qualified to perform the 12-point assessment. Exporters should track UL’s Standards Updates portal and subscribe to UL’s regulatory bulletins for procedural clarifications ahead of June 2026.

Assess TLS 1.3 integration depth in current firmware versions

TLS 1.3 is not backward-compatible with TLS 1.2 at the handshake level. Companies must verify whether their existing stack supports full RFC 8446 compliance — including mandatory AEAD cipher suites, 0-RTT restrictions, and key derivation logic — rather than partial or wrapper-based implementations. Integration gaps may necessitate vendor SDK updates or custom porting efforts.

Initiate internal firmware security review against the 12 audit criteria

The listed areas (e.g., “secure key storage”, “firmware image authenticity validation”) reflect concrete technical controls — not high-level policy statements. Engineering teams should map current codebase practices to each criterion now, identifying gaps in build-time signing workflows, runtime memory isolation, or debug interface lockdown — especially where third-party libraries are used.

Coordinate with component suppliers on joint certification timelines

For systems integrating multiple V2G components (e.g., meter + controller + comms module), UL may require traceability across firmware versions and audit reports. Exporters should align with suppliers on version-controlled documentation handover and shared timelines to avoid bottlenecks during submission.

Editorial Perspective / Industry Observation

Observably, this update signals a structural shift in UL’s approach to cybersecurity in grid-edge devices: from evaluating standalone encryption features to requiring verifiable, end-to-end firmware security discipline. It is less a one-off compliance checkpoint and more an early indicator of how future editions of UL 1998 — and potentially IEEE 2030.5 or ISO 15118-aligned standards — may treat cryptographic assurance. Analysis shows that the emphasis on source-code–level audit (not just binary testing) reflects growing regulatory attention to software supply chain integrity in critical infrastructure-adjacent applications. From an industry perspective, this is currently best understood as a binding procedural milestone — not merely advisory guidance — with enforceable impact on U.S. market access starting June 2026.

Conclusion: UL’s Supplement A1 to UL 1998-3rd formalizes minimum cryptographic and firmware security expectations for V2G devices entering the U.S. market. Its significance lies not in introducing entirely new concepts, but in codifying them into mandatory, auditable, and time-bound requirements. For affected stakeholders, the update is best interpreted as a concrete operational deadline — not a distant policy signal — demanding technical readiness in both protocol implementation and security documentation practices.

Information Source: UL Solutions official announcement, UL 1998-3rd Edition Supplement A1 (published April 28, 2026). Note: Detailed audit report templates and updated lab recognition lists remain pending; ongoing monitoring is recommended.