Category: Supply Chain Risk Management

Software Bill of Materials

Also known as:

Simply put

A Software Bill of Materials (SBOM) is essentially a list of ingredients for a piece of software, identifying the various components used to build it. Much like a food label lists ingredients, an SBOM records the components, including open source and third-party pieces, that make up a software product. It has become a key building block for managing software security and software supply chain risk.

Formal definition

An SBOM is a formal record containing the details and supply chain relationships of the various components used in building software. As commonly described, it functions as a nested inventory of software components, which may include third-party and open source libraries, artifacts, licenses, scripts, and package or version information. SBOMs are treated as a foundational element of software supply chain risk management; readers should verify current authoritative specifications, required data fields, and applicable format standards against the governing guidance, as these details and their contractual or regulatory applicability are outside the scope of this definition.

Why it matters

Modern software is rarely built from scratch; it is assembled from open source libraries, third-party components, and reused code. This composition creates a software supply chain in which a vulnerability or licensing issue in a single dependency can propagate into many downstream products. An SBOM addresses this by providing a nested inventory of the components that make up a software product, giving organizations the visibility needed to identify what they are actually running and to respond when a component is later found to be affected by a vulnerability. CISA describes the SBOM as a key building block for software security and software supply chain risk management, reflecting its role as a foundational artifact rather than a standalone control.

Without an accurate component inventory, organizations struggle to answer a basic but critical question: which of our systems contain a given vulnerable component? An SBOM helps convert that question from a lengthy investigation into a lookup exercise, supporting faster triage and remediation. It also aids in tracking license obligations attached to open source and third-party components, which is relevant to both legal and operational risk.

Readers should note that an SBOM enables risk management but does not by itself constitute security or compliance. Producing an SBOM is not the same as remediating the vulnerabilities it may help surface, and the specific data fields, format standards, and any contractual or regulatory requirements for SBOMs are outside the scope of this definition. Whether an SBOM is required, and in what form, depends on the applicable guidance and agreements, which the reader should verify against current authoritative sources.

Who it's relevant to

Software producers and government contractors

Organizations that build or deliver software may be expected to generate and provide SBOMs as part of software supply chain risk management. Because whether an SBOM is contractually or regulatorily required, and in what form, is outside the scope of this definition, producers should verify current obligations, required data fields, and format expectations against the applicable guidance and their agreements.

Information system security managers and security teams

Security personnel can use SBOMs as a foundational input for vulnerability management, using the component inventory to identify which systems may contain a newly disclosed vulnerable component. An SBOM supports this work but does not replace remediation; producing or receiving an SBOM is not equivalent to securing the software.

Compliance officers and auditors

Those assessing software supply chain practices may treat the presence, completeness, and currency of SBOMs as evidence of supply chain risk management maturity. They should confirm which authoritative standards and any applicable requirements govern SBOM content and format for the systems in scope, as these details evolve and vary by context.

Procurement and acquisition personnel

Staff involved in acquiring software may consider SBOMs when evaluating and comparing the composition and associated licensing of third-party and open source components in a product. Any specific SBOM requirements to be imposed through acquisition should be verified against current authoritative guidance rather than assumed from this definition.

Inside SBOM

Component Inventory

An itemized list of the software components, libraries, and modules that make up a given software product, including both first-party and third-party or open-source elements.

Component Identifiers and Version Information

Data identifying each component and its version, which supports mapping components to known vulnerabilities. The specific identifier schemes used depend on the SBOM format and implementation.

Supplier and Author Information

Attribution indicating who supplied or authored each component, supporting supply chain transparency and accountability.

Dependency Relationships

Information describing how components relate to and depend upon one another, so that transitive dependencies are visible rather than only top-level components.

Machine-Readable Format

SBOMs are generally expressed in structured, machine-readable formats to enable automated ingestion and analysis. Common formats exist in the marketplace, but the appropriate choice should be confirmed against the consumer's requirements and current authoritative guidance.

Common questions

Answers to the questions practitioners most commonly ask about SBOM.

Does having an SBOM mean my software is secure or compliant?

No. An SBOM is an inventory artifact that documents the components, libraries, and dependencies within a software product; it does not by itself remediate vulnerabilities or establish that a system is secure. Generating an SBOM is distinct from analyzing it, acting on the vulnerabilities it may reveal, or meeting any particular compliance requirement. Treat an SBOM as an input to risk management and vulnerability management processes rather than as evidence of security or compliance in itself. Confirm any specific compliance obligation against the current authoritative source that applies to your program.

Is an SBOM a one-time deliverable I can produce and file away?

Generally, no. Software composition changes as components are updated, patched, or replaced, and newly disclosed vulnerabilities can affect components that were considered clean at the time of generation. In most implementations an SBOM is expected to be maintained and regenerated to reflect the current build, and to be paired with ongoing vulnerability monitoring. Treating an SBOM as a static, point-in-time document rather than a living artifact tied to your build and monitoring processes undermines its value. Verify the currency and update expectations against the applicable guidance or contract.

What formats are commonly used to produce an SBOM?

SBOMs are typically produced in machine-readable formats intended to support automated exchange and analysis. Commonly referenced formats in the community include SPDX and CycloneDX, among others. The appropriate format for a given engagement may be specified by the acquiring party or by applicable guidance, and format expectations continue to evolve. Confirm which format, fields, and level of detail are required for your specific program against the current authoritative or contractual source rather than assuming a single format is universally accepted.

Where in the software lifecycle should an SBOM be generated?

SBOM generation is generally most reliable when tied to the build or release process, so that the recorded components correspond to what is actually shipped or deployed. Generating from build artifacts rather than reconstructing composition after the fact tends to improve accuracy. Because different organizations and tools integrate SBOM generation at different points, and expectations may differ by program, confirm the specific lifecycle stage, tooling, and depth of dependency capture required for your environment against the applicable guidance.

Who is expected to produce the SBOM, and who consumes it?

In typical arrangements the software supplier or producer generates the SBOM, while the acquiring organization consumes it to support vulnerability management, supply chain risk decisions, and inventory. Responsibilities can vary depending on contractual terms, the nature of the relationship between supplier and acquirer, and any applicable requirements. Because roles and obligations are commonly defined by the specific agreement or guidance that applies, confirm who must produce, deliver, and maintain the SBOM against your current authoritative source.

How does an SBOM fit into vulnerability and supply chain risk management workflows?

An SBOM is generally used as an input that lets an organization map disclosed vulnerabilities to the components present in its software, supporting more informed prioritization and response. To be useful in practice it is typically integrated with vulnerability data sources and monitoring processes rather than reviewed in isolation. The precise workflow, tooling, and cadence depend on the organization and any applicable requirements, so confirm how SBOM data must be handled and acted upon against the guidance or contract that governs your program.

Common misconceptions

Producing an SBOM makes a software product secure or compliant.

An SBOM is a transparency artifact that documents composition; it does not by itself remediate vulnerabilities or establish compliance. As with the broader principle that compliance is not the same as security, an SBOM must be paired with vulnerability management, monitoring, and risk decisions to have security value.

An SBOM is a one-time deliverable that stays accurate over the life of the software.

Software composition changes as components are updated, patched, or replaced, so an SBOM generally reflects a specific build or version at a point in time. It typically must be regenerated and maintained to remain accurate, and readers should verify currency expectations against applicable requirements.

SBOM requirements are uniform across all federal, defense, and other sectors.

Expectations for whether and how an SBOM must be provided can differ across federal civilian, defense, and other environments and are evolving. Practitioners should confirm the specific obligations, formats, and scope against current official sources and any applicable contractual terms rather than assuming a single standard applies.

Best practices

Generate SBOMs in a structured, machine-readable format so they can be ingested and analyzed automatically rather than reviewed only by hand.

Include transitive dependencies and not just top-level components, so that hidden or nested third-party and open-source elements are visible.

Regenerate and update the SBOM whenever the software's composition changes, treating it as a version-specific artifact tied to each build rather than a static document.

Use the SBOM as an input to vulnerability management by mapping documented components and versions against known vulnerabilities, rather than treating SBOM production as an end in itself.

Capture supplier and author information for components to support supply chain transparency and accountability.

Confirm the required SBOM format, contents, and delivery expectations against the applicable current authoritative guidance and any contractual terms, since requirements vary by environment and are evolving.