XBOM

eXtended Bill of Materials

A comprehensive framework for tracking all components, dependencies, and supply chain elements across the full product lifecycle -- from silicon to software to service.


Software
Hardware
Supply Chain

Taxonomy

What is SBOM?

A Software Bill of Materials (SBOM) is a formal, machine-readable inventory of software components and dependencies, including their versions, licenses, and known vulnerabilities. Required by U.S. Executive Order 14028 (2021) for federal software procurement.

What XBOM Extends

XBOM extends SBOM by encompassing hardware components (HBOM), firmware dependencies (FWBOM), AI model lineage (AIBOM), service and API dependencies (SvcBOM), and supply chain provenance data. It creates a unified transparency framework across all product layers.

Component Types

XBOM recognizes six component classes: binary artifacts, source packages, hardware modules, firmware images, trained models, and service endpoints. Each class has standardized metadata fields and vulnerability tracking requirements.

SBOM

Software Bill of Materials. Enumerates all software components, libraries, and dependencies in a product.

Format: SPDX, CycloneDX

HBOM

Hardware Bill of Materials. Tracks physical components, chip vendors, and manufacturing origins.

Scope: PCB, SoC, Module

AIBOM

AI Bill of Materials. Documents training data provenance, model architecture, and fine-tuning lineage.

Status: Emerging standard

VEX

Vulnerability Exploitability eXchange. Companion to SBOM indicating whether known vulnerabilities are exploitable in context.

Format: CSAF, CycloneDX

SvcBOM

Service Bill of Materials. Enumerates API dependencies, cloud services, and third-party integrations.

Scope: API, SaaS, IaaS

Architecture

PRODUCT SOFTWARE LAYER App Libs Deps OS FIRMWARE LAYER BIOS/UEFI BMC FW NIC FW HARDWARE LAYER CPU RAM SSD NIC SUPPLY CHAIN Vendor A Vendor B Vendor C

SBOM Software Bill of Materials

A machine-readable inventory listing all components within a software product, including open-source libraries, proprietary modules, and their transitive dependencies. SBOM generation can be performed at build time (source analysis) or post-build (binary analysis).

Standards: SPDX (ISO/IEC 5962:2021), CycloneDX (OWASP), SWID (ISO/IEC 19770-2)


HBOM Hardware Bill of Materials

A structured record of every physical component in a hardware product, from system-on-chip architectures to passive components. HBOM tracks manufacturer origin, part numbers, fabrication facilities, and component lifecycle status.

Key fields: MFR_ID, PART_NO, FAB_LOC, EOL_DATE


VEX Vulnerability Exploitability eXchange

A companion document to SBOM that communicates whether a known vulnerability in a component is actually exploitable in the context of the specific product. VEX reduces alert fatigue by distinguishing between theoretical and practical risk.

Statuses: Not Affected, Affected, Fixed, Under Investigation


Supply Chain Provenance

The documented origin and chain of custody for every component in a product. Provenance tracking enables organizations to verify that components have not been tampered with and that they originate from approved suppliers.

Mechanisms: in-toto attestations, SLSA framework, Sigstore signatures


AIBOM AI Bill of Materials

An emerging standard for documenting AI/ML model components, including training dataset provenance, model architecture, hyperparameters, fine-tuning history, and evaluation metrics. Critical for AI governance and regulatory compliance.

Tracks: DATASET_SRC, MODEL_ARCH, TRAIN_PARAMS, EVAL_METRICS

SBOM
HBOM
VEX
Provenance
AIBOM