PBOM vs SBOM – Building a Complete Security Bill of Materials

The software supply chain has become one of the most contested battlegrounds in security.

Modern applications are no longer made up of monolithic code. They’re assembled from thousands of moving parts, including open-source libraries, commercial components, and proprietary modules ,  all stitched together inside fast-moving pipelines. 

When even one of those pieces is compromised, the ripple effect can be enormous. SolarWinds and Log4j proved just how quickly a single flaw can cascade into a global incident.

To bring order to this complexity, the industry turned to a familiar idea from manufacturing: the Bill of Materials (BOM). In factories, a BOM catalogs every part in a product. In software, it serves a similar purpose, but with higher stakes. It documents not only what goes into an application, but increasingly, how it was put together.

Two artifacts are at the center of this shift:

1. The Software Bill of Materials (SBOM) lays out a transparent inventory of application components, forming the foundation for compliance and vulnerability management. 
2. The Pipeline Bill of Materials (PBOM) goes further, capturing the full build story ,  commits, environments, security scans, and runtime conditions ,  to create an auditable ledger of trust.

The comparison of PBOM vs SBOM signals more than a technical distinction. It reflects a new reality: transparency alone is no longer enough. 

What organizations need now is integrity, traceability, and continuous validation. Working together, SBOM and PBOM establish a complete security Bill of Materials, one that doesn’t just describe software, but proves it can be trusted.

Key takeaways

• SBOMs provide transparency. They act as an inventory of software components, enabling compliance and vulnerability lookup.
• PBOMs provide trust. They capture how applications were built, adding context, integrity, and traceability.
• Together, they complete the picture. Integrating SBOM and PBOM creates a defensible, auditable foundation for supply chain security.

Key Differences Between SBOM and PBOM

Although both are Bills of Materials, SBOMs and PBOMs serve very different purposes in the software supply chain. One captures what goes into an application. The other records how it was built. Together, they address two sides of the same challenge: transparency and integrity.

At its core, an SBOM is a static inventory. It lists every library, dependency, and module in an application, essential for identifying vulnerabilities, tracking licenses, and meeting compliance requirements. But it’s limited to a snapshot in time, offering no visibility into whether a vulnerability is exploitable or whether the build process itself was tampered with.

A PBOM, in contrast, is a dynamic, continuous record of the development pipeline. It captures commits, build configurations, security scans, and deployment data. This context transforms an SBOM from a simple component list into a verifiable artifact, backed by evidence of a secure build process.

Here’s a side-by-side comparison to highlight the distinction:

Attribute	SBOM	PBOM
Core purpose	Transparency: what’s inside an application	Integrity and traceability: how the application was built
Scope	Product-focused (dependencies, licenses, components)	Process-focused (commits, build logs, runtime configs)
Data type	Static snapshot	Continuous event log
Primary use case	Vulnerability lookup, license compliance, reporting	Supply chain integrity, forensic analysis, contextual risk prioritization

Related Content: What is a software bill of materials (SBOM)?

How PBOM Adds Real-Time Pipeline Context to the BOM

An SBOM answers “what’s inside,” while a PBOM answers “how it was made” with evidence you can trust. 

That shift from a static list to a living record is what turns component transparency into operational security.

What PBOM records in practice

Source control lineage: commit hashes, authors, code reviews, branch protection status, and the exact pull request that introduced a change.	Build environment details: CI job IDs, build scripts, compiler and dependency hashes, container base images, and signatures for intermediate artifacts.	Security controls telemetry: results from SAST, DAST, SCA, secrets scanners, IaC checks, and policy gates, including timestamps and pass/fail states.
Configuration and deployment context: Infrastructure as Code, service manifests, image digests, environment variables, and whether a service is internet-exposed, behind a WAF, or internal-only.	Ownership and approval trail: code owners, reviewers, exceptions granted, and risk acceptances tied to specific commits or builds.	Attestations and signatures: cryptographic proofs that a build ran in a trusted environment and that artifacts were not tampered with in transit.

Why this context changes outcomes

• Exploitability over existence: SBOMs surface known issues; PBOMs reveal whether those issues are reachable. Example: a critical CVE appears in a transitive library. The PBOM shows the vulnerable function is never invoked, the service is not externally reachable, and a compensating control blocks the path. That insight cuts noise and focuses remediation on real risk, not theoretical risk.
• Build integrity you can verify: A component list cannot tell you if the build runner was compromised. PBOM evidence can flag an unsigned step, a drift in compiler hash, or an unexpected script invocation between scan and package, which would otherwise slip past a static artifact.
• Faster incident response: When an alert lands, PBOM data shortens time-to-truth. You can trace a runtime indicator back to the exact commit, developer, and pipeline run, view all scans that executed, and see the deploy that carried the change to production.
• Better SBOM security: PBOM context enriches an SBOM with provenance, signatures, and links to the pipeline evidence that produced it. That turns the SBOM from a document into a defensible artifact suitable for audits and third-party assurance.
• Policy you can automate: With a continuous event trail, you can enforce “no deploy” conditions when required scans fail, when IaC changes increase exposure, or when a high-risk package appears without an approved owner. The same evidence supports risk-based exceptions with time-boxed, auditable approvals.
• Cleaner handoffs with VEX: PBOM findings feed VEX statements that indicate whether a listed vulnerability is exploitable in your environment. Consumers of your software can filter irrelevant CVEs immediately, reducing triage churn.

A quick walkthrough

A new CVE drops for a JSON parser in your dependency graph.

1. Locate and scope: SBOM tools flag affected versions.
2. Qualify with context: The PBOM links the affected digest to a specific build, shows the parser is used only in an internal admin path, and that input validation blocks untrusted sources. Static analysis confirms the vulnerable method is not called.
3. Decide with evidence: You gate external releases, raise an internal priority to patch, attach a VEX statement that marks the issue as not exploitable, and capture all of it in the PBOM. The result is a documented, defensible decision instead of a blanket fire drill.
   

Where to plug this into your pipeline

• Automate SBOM generation at build and then sign and attach PBOM evidence so each release artifact ships with its own provenance. Teams adopting CI/CD pipeline security best practices can ensure those attestations are meaningful and enforceable.
• Correlate runtime to code so production findings map to repositories, owners, and the pipeline run that delivered them. This helps organizations go beyond OSS dependencies with your SBOM and prioritize by actual exposure, not just package lists.

Automating SBOM Generation vs PBOM Usage in CI/CD

Operationalizing a BOM requires two very different approaches. SBOM automation is about producing a document at a specific moment, while PBOM usage is about capturing evidence continuously.

SBOM automation in practice

Generating an SBOM is usually a discrete pipeline step. Tools such as Syft, Trivy, and CycloneDX generators scan source code, container images, or build artifacts to create a machine-readable inventory. 

Teams often configure these tools as GitHub Actions, Jenkins jobs, or GitLab CI steps. With every build, a fresh SBOM is created, providing developers and auditors a transparent view of dependencies.

That automation is critical for compliance and vulnerability management. Each new release ships with a signed SBOM, making it possible to answer quickly when a new CVE is disclosed. This step ensures you always have an accurate, point-in-time inventory.

Related Content: A practical guide to SBOM

PBOM usage in practice

A PBOM works differently. It doesn’t run as a one-off scan. Instead, it integrates across the entire CI/CD pipeline, listening for commits, builds, scans, and deployments. 

Every event is recorded and cryptographically signed, forming a ledger that tells not only what was built but how it was built.

This continuous evidence capture changes the nature of pipeline assurance. Instead of simply producing an artifact at the end, the PBOM acts as a passive observer, validating the process itself. That distinction matters: SBOM automation is active and imperative; PBOM collection is declarative and persistent.

Why both matter

• Compliance baseline: Regulatory frameworks require a standard SBOM. Automating its generation ensures you can meet those obligations without slowing delivery.
• Integrity and trust: A PBOM underpins that SBOM with a tamper-evident history of the build process. This turns an SBOM from a static document into a trustworthy artifact.
• Stronger pipeline security: When paired with CI/CD pipeline security best practices, PBOMs ensure attestations reflect a secure build environment.
  

In short, SBOM automation provides the snapshot, while PBOM usage provides the context. Both are required if organizations want their Bills of Materials to stand up to scrutiny.

The push for a PBOM standard

While SBOMs benefit from established formats like SPDX and CycloneDX, the PBOM standard is still evolving. 

There isn’t yet a universally recognized schema for capturing pipeline events, but the direction is becoming clear.

Early momentum

Commercial vendors have pioneered their own approaches to PBOM, showing the value of continuous evidence in securing the software supply chain. 

At the same time, community-driven initiatives like pbom.dev have built frameworks like the Open Software Supply Chain Attack Reference (OSC&R), which catalogs tactics and techniques specific to pipeline attacks. These efforts give security teams a shared language for describing the risks PBOMs are designed to mitigate.

Leveraging existing ecosystems

Rather than starting from scratch, the industry is looking to extend proven standards. CycloneDX, for example, introduced the Operations BOM (OBOM) format to describe runtime configurations, services, and dependencies beyond the build artifact itself. 

OBOM’s mission aligns closely with PBOM: capturing a full-stack view of how software is created and deployed. By building on such extensible schemas, PBOM data could become interoperable with the broader SBOM ecosystem, including the tools already in wide use.

Why this matters

A formal PBOM standard would do more than simplify integration. It would enable organizations to build centralized inventories that unify SBOMs, PBOMs, and runtime context into a single source of truth. That level of visibility is critical for mature software supply chain risk management. It would also give regulators, customers, and auditors confidence by elevating PBOMs from vendor artifacts to verifiable industry records.

Best Practices for Implementing SBOM and PBOM Together

The strongest approach to supply chain security doesn’t pit SBOM and PBOM against each other. Instead, it combines their strengths into a unified strategy, where the SBOM acts as a compliance-ready artifact and the PBOM provides the evidence that the artifact can be trusted.

Treat the SBOM as a PBOM artifact

Every SBOM generated during the build should be backed by the PBOM ledger. Cryptographic signatures, commit hashes, and job IDs link the SBOM to the exact pipeline run that produced it. 

This ensures consumers can verify that the SBOM reflects the true state of the artifact, not a tampered version.

Enrich SBOMs with PBOM context

Pairing component inventories with pipeline evidence turns static lists into actionable intelligence. 

When an SBOM includes links to associated security scans, infrastructure configs, and runtime exposure, it evolves from a compliance document into a self-validating record of SBOM security.

Automate and continuously verify

Robust SBOM automation ensures every build produces a fresh inventory. At the same time, the PBOM continuously verifies that the generation process itself is secure. 

This dual approach guarantees that SBOM tools are operating in a trusted environment and that the resulting outputs remain accurate.

Integrate VEX for noise reduction

PBOM data provides the inputs for accurate VEX statements, clarifying which vulnerabilities are exploitable in practice. 

By attaching VEX to an SBOM, organizations can filter irrelevant alerts at scale, cutting through noise and focusing on real risks.

Centralize BOM management

A single platform that unifies SBOM and PBOM data provides version control, historical records, and a consolidated view of the software supply chain. This approach makes it easier to respond to new disclosures, meet audit requirements, and track how risks evolve over time.

For teams looking to embed these practices into development workflows, Apiiro Develop offers guidance on integrating BOM management into CI/CD and beyond.

Unify SBOM and PBOM to improve software supply chain security

The evolution from SBOM to PBOM reflects a broader shift in how organizations approach software supply chain security. 

SBOMs deliver the transparency regulators require, but their static nature limits what they can prove. PBOMs bring the missing context ,  the ledger of commits, builds, scans, and deployments that transforms lists of components into evidence of integrity.

The conversation shouldn’t be PBOM vs. SBOM, but how the two work together. SBOMs document what is inside an application, while PBOMs verify how it was made. When combined, they create a complete security BOM, one that both meets compliance requirements and provides continuous assurance against tampering and exploitable vulnerabilities.

Apiiro helps organizations get there faster by embedding dynamic visibility into the software architecture itself, from code to runtime. With deep analysis, contextual risk prioritization, and continuous validation, teams can integrate SBOMs and PBOMs seamlessly into their pipelines without slowing innovation.

Ready to strengthen your software supply chain? Book a demo to see how you can operationalize SBOM and PBOM together.

Frequently asked questions

How does PBOM help security teams understand runtime risks missing from SBOM alone?

An SBOM lists every component, including those never used at runtime. A PBOM captures pipeline evidence, runtime configurations, and deployment context. This shows which vulnerable components are actually loaded, reachable, or exposed, allowing teams to prioritize remediation based on real-world risk instead of theoretical vulnerabilities.

Can PBOM replace SBOM for regulatory compliance purposes?

Not today. Regulations like the U.S. Executive Order and EU Cyber Resilience Act specifically require an SBOM in formats such as SPDX or CycloneDX. A PBOM is best used to generate and validate those SBOMs, ensuring they are accurate, tamper-evident, and backed by pipeline evidence.

What metrics indicate successful adoption of PBOM in CI/CD workflows?

Key metrics include reduced Change Failure Rate, lower Mean Time to Recovery, and increased deployment frequency without a spike in security incidents. Each demonstrates that PBOM evidence is improving integrity checks, accelerating incident response, and enabling teams to release software faster while keeping risk under control.

Are there tools or standards emerging to support PBOM generation automatically?

Yes. While the formal PBOM standard is still emerging, efforts like CycloneDX OBOM offer a strong foundation. Vendors are building platforms that capture pipeline events automatically, while open communities like pbom.dev are developing frameworks to define common PBOM data models and threat scenarios.

Should both SBOM and PBOM be maintained long-term, or only PBOM for continuous risk?

Both serve unique purposes. SBOMs should be versioned and archived with each release as immutable compliance artifacts. PBOMs act as a continuous, living ledger of the pipeline, providing ongoing assurance. Maintaining both ensures organizations meet regulatory requirements and retain verifiable evidence of supply chain integrity.