Are Open-Source Libraries Now Legally Supply Chain Risks Under NIS 2?
Every business now faces a compliance reckoning: open-source libraries are no longer background filler-they are full third-party risks and legal exposures under NIS 2. European auditors treat every library in your stack, from the smallest helper module to foundational frameworks, as if they carried revenue-bearing supplier contracts. If your ISMS, policies, or board reporting dismiss open-source as “freeware,” you are inviting audit gaps and regulatory scrutiny.
NIS 2 draws no line between bought and borrowed; every external code block you depend on is a supply chain risk.
This shift is codified by ENISA and national authorities: complete OSS inventories, explicit risk evaluations, and traceable controls are non-negotiable. If you’re running production workloads on a patchwork of untracked open-source dependencies, every line of code you didn’t author could become a compliance breach, a supply chain incident, or a liability you never saw coming. For board members, IT leaders, and compliance owners, opacity around your open-source stack is both a business risk and a regulatory one-auditors will expect you to demonstrate the same duty of care for OSS as for commercial vendors.
The Regulatory Baseline: OSS = Supplier, Unless Proven Otherwise
The NIS 2 Directive (Art. 21-22) and ENISAs guidelines demand that any code, service, or library not fully built and managed in-house is presumptively a third-party risk-regardless of licence, payment terms, or the presence of a formal contract. This principle extends not just to direct dependencies (components you intentionally include) but also to all indirect, transitive dependencies silently brought in by developer tooling. If you dont own it, youre responsible for it.
Whats changed? Legal and regulatory frameworks now define supplier in operational terms. ENISA: Usage of open-source software must be accompanied by adequate risk assessment and supply chain control, just as with any commercial vendor (ENISA, 2024).
Key takeaways:
- Your software bill of materials (SBOM) must include every open-source component, with version and provenance traceable on demand.
- Every library is a risk unless an explicit, continuous due diligence record proves otherwise.
- Boards and senior management are responsible for demonstrating supplier oversight for OSS-delegation to the tech people no longer cuts it.
No longer is OSS a technical bonus running outside your compliance regime. It is now regulated supply chain criticality-every bit as much as cloud, SaaS, or consultancy inputs.
Book a demoWhat Happens If You Ignore OSS as Third-Party Risk?
Treating open-source as “not real supply chain” is exactly the blind spot that modern attackers-and now, regulators-exploit. Most organisations running commercial platforms or SaaS products rely on hundreds, sometimes thousands, of external libraries, many installed as “shadow dependencies” without explicit review or ownership in any engineering ticket. This silent proliferation seeds vulnerabilities-technical, legal, or operational-that can trigger regulatory fines, service outages, or lasting brand harm.
Security failures rarely announce themselves-they’re hidden in the parts no one claims ownership for.
The Attack & Audit Reality: Compound Exposure Multiplier
- Supply Chain Attacks: Incidents like log4j and the XZ Utils compromise (Herbert Smith Freehills, 2024) prove sophisticated adversaries are probing open-source maintainers, development pipelines, and distribution platforms as weak links. The cascading risk is not theory-it is daily practise in the wild.
- Audit & Incident Reporting: Under NIS 2, being unable to instantly enumerate and evidence your OSS dependencies, patch status, or owner can constitute a governance failure. ENISA repeatedly warns: “Delays in responding to OSS vulnerabilities directly correlate with increased incident risk and regulatory exposure” (ENISA, 2024).
The Invisible Admin Burnout
Manual logs, spreadsheets, or delegated “security scans” cannot keep pace. Each cycle you delay in updating, tracking, or remediating OSS adds not just technical debt but legal liability. A single unpatched library, one missed critical update, or a licence gap exposes boards to regulator queries and-now-potential administrative fines or public reprimand. And when workforce exhaustion or tool fragmentation triggers a slip, the gap widens fast: every missing owner, every update lag, every unclear policy maps to a new entry in your risk register and a red flag for auditors.
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What Exactly Does NIS 2 Demand for Open-Source Software?
Both the letter and spirit of NIS 2 are now explicit: if you use third-party code, you must demonstrate identification, assessment, ongoing management, and evidence for your dependencies. This does not stop with the first layer-transitive dependencies count. ENISA and most national regulators now expect to see all of the following documented:
- A Complete, Auditable Inventory (SBOM)
- Keep your SBOM live and complete-recording every open-source and commercial library, version, and provenance (down to minor plugins).
- The inventory must be updated on every build and deployment, and quickly exportable for regulator or auditor review.
- Component-Level Risk Assessment
- For each dependency: assign a risk owner, note criticality, licence (and provenance) status, CVE exposure, and how it could impact your systems.
- ENISA: “Material dependencies require explicit risk status and ownership assignment” (ENISA, 2024).
- Evidence of Ongoing Review, Remediation, and Ownership
- Every event (new component, update, CVE) gets a timestamped log. Every licence is reviewed and record kept, every escalation or patch mapped to an explicit owner and control.
- Auditors expect to see automation-no “one-time processes or annual reviews.”
Translating Law to Controls: Table Bridge
Below is a quick-reference bridge table showing how NIS 2, ISO 27001, and operational best practise converge on OSS risk management:
| NIS 2 Demand | Example Operationalisation | ISO 27001 / Annex A Reference |
|---|---|---|
| Track all external code | Live SBOM updated with every deployment | A5.21, A8.8, A8.14 |
| Assign and document risk ownership for OSS | Policy linking, owner in ISMS | A5.19, A5.20, 6.1.2, 6.1.3 |
| Licence, provenance, and evidence review | Licence scan, attach docs to risk record | A8.1, A9, 7.5 |
| Track mitigation for all critical CVEs | Patch log, automated update status log | A5.8, A8.8, A8.33 |
| Map OSS to the SoA and key policies | Link every SBOM item to SoA & controls | SoA, A5.1, A5.3 |
Translation for teams: If you’re using open-source, treat it with the same gravity as your paid SaaS provider-full onboarding, risk assignment, decision records, and live status updates.
What Defines Proper Due Diligence for Open Source Under NIS 2?
Legal obligations are uniform: open-source, like paid software, now demands end-to-end due diligence and supplier controls, even if its authors are anonymous volunteers. This obligation is measurable:
The Due Diligence Essentials
- Licence and Origin Review: Every OSS artefact needs documented licence checks. Any uncertainty, restrictive term, or ambiguity must trigger escalation before use. For many frameworks (especially copyleft or AGPL), a missed clause can retroactively force you to open-source proprietary code, triggering instantly material supply chain risk.
- Security Assessment: Look beyond “does it work?” to “does it come with a security policy, update cadence, and CVE management process?” Record proof of review; highlight any “unmaintained” status as a flagged risk.
- Automated Monitoring: “Set and forget” does not comply. Implement SBOM & vulnerability scanning with notifications-ideally directly into your ISMS-to surface, record, and route every event.
- Transitive Dependency Tracking: Use tools to get two or more layers deep-transitive, shadow, or developer-only dependencies all create real exposure. Any “tooling only” code in production is now a compliance event if untracked.
- Ownership Assignment & Evidence Logging: Even the smallest code chunk must have a named internal owner. Evidence is not optional-document every step, every approval, every review.
Due Diligence Traceability: Table
| Trigger | Action | Linked Control | Evidence Logged |
|---|---|---|---|
| Add new OSS | Review licence, assign owner | SoA, A5.21 | SBOM log, review doc |
| CVE emerges for any library | Assess, remediate, log | A8.8, A5.20 | Patch/incident log |
| Licence gap or ambiguity | Legal escalate, hold deploy | A9, A5.19 | Legal review note |
| Library deprecated/obsolete | Replace/patch, document | A8.14, A8.8 | Update note, email record |
Without automated evidence logs, even the best-documented policies can fall apart under audit.
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Why Do Regulators Demand Continuous OSS Monitoring and Automation?
The threat landscape and regulatory response move much faster than manual intervention. The only sustainable answer, and audit-safe approach, is “continuous automation”:
Every time your stack changes, so must your supply chain oversight-because risk flows incrementally, not once per year.
Live SBOM: Audit-Ready at All Times
- Each code push triggers update in the SBOM and ISMS, linked to every relevant control, risk, and policy.
- Vulnerability discovery (e.g., CVE) routes automatically to the assigned risk owner, who receives evidence-based To-dos and update prompts.
- Policy/control updates or staff changes are recorded as soon as they occur, with full audit-trail.
- Remedial action is recorded at every step: notification → response → fix → evidence log.
ENISA’s verdict: “Software Bill of Materials must be ‘live’, not annual, with near-real-time updates traceable for audit and remediation” (ENISA Open Source Security Guidelines 2024).
How Should You Document and Evidence OSS Compliance for Audit?
NIS 2 and best practise demand that all OSS compliance data be “audit-ready”: instantly exportable, time-stamped, and traceable from supply to update to removal.
Five Steps to Effective Documentation:
- Instant SBOM Export: Your SBOM should be a living asset, not just a project artefact. Associate every library with policy references, responsible owner, and controls.
- Event Logging: Every time you add, update, remove, or fix a component, log it. Timestamp, owner, action, and status are mandatory.
- Comprehensive Supply Map: Use a system that tracks all open-source and commercial suppliers from initial selection to end-of-life or replacement.
- Incident & Patch Escalation Audit-Trail: Any issue, review, or event escalates to the risk owner; resolution or mitigation is logged, linked, and reviewable.
- Ownership and Gaps: No matter how big or small the component, assign ownership and check for orphaned or unacknowledged libraries-these are audit and compliance risks.
Workflow tables and dashboards in modern ISMS platforms make this a continuous, “always-on” audit posture rather than a scramble before annual review.
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What Does an Integrated, Audit-Safe ISMS Workflow for OSS Look Like?
Futureproofed compliance with NIS 2, ISO 27001, ENISA, and emerging frameworks like NIST SSDF comes from embedding third-party risk controls, SBOM logic, evidence tracking, and owner assignment within everyday workflows:
- Every installed OSS is a live entry in the SBOM, with owner, status, update date, and policy cross-link.
- Risk assessment for new dependencies is seamlessly tied to the onboarding ticket, the SoA update, and audit controls (mapping to A5.19, A5.21).
- Vulnerability checks and licence scans feed directly into alert systems and tasking (so action is assigned, not lost).
- All evidence-scan reports, risk reviews, acknowledgements, updates-is a click away, retrievable for both incident response and audit.
- When risks or controls change, gap reports and board dashboards show status in real time-allowing leaders to identify and close exposures before regulators do.
Operational compliance is what happens between audits, not just before them.
How Do You Cross-Map All the Pieces-OSS Inclusion, Controls, and Audit Requirements-Across NIS 2, ISO 27001, and ENISA Guidance?
The essence of defensible compliance is traceable integration: SBOM entries, SoA controls, risk register updates, ownership assignments, and evidence must form a web-no loose threads.
| OSS Trigger | Audit Response | ISO 27001 Reference | NIS 2 Article |
|---|---|---|---|
| New OSS dependency | Assign owner, risk status, check licence | A5.19, A5.21 | Art. 21, 22 |
| Vulnerability found | Patch or mitigate, log in risk register | A8.8, A8.14 | Art. 21 |
| Policy/procedure update | Evidence log, acknowledge staff in To-dos | A7.3, A7.5, A5.1 | Art. 21, 25 |
| Scheduled review | Gap analysis, documentation export | Clauses 9.1–9.3 | Art. 41+ |
Cross-map tools and periodic diagnostic routines can help surface mismatches-where, for example, the SBOM is missing a licence, the SoA lacks an owner assignment, or a risk review is overdue.
Ready for Resilience Capital? Making OSS Evidence Your Board’s Security Story
Audit confidence is now built on everyday resilience, not last-minute evidence sprints. The companies most trusted by boards and regulators are those who treat open-source oversight as both a business and compliance advantage-maintaining living registers, cross-mapping controls, and embedding ownership and evidence throughout the workflow.
Being audit-ready is proof of operational control, not just regulatory obedience.
Want to move OSS from hidden risk to reputational win?
- Shift to a platform with continuous SBOM, ownership assignment, evidence logging, and live policy mapping.
- Encourage cross-team adoption with auto-generated To-dos and dashboards for practitioners and leadership alike.
- Transform audits into operational showcases, not tripwires-making every regulator or board query proof of strength.
Don’t allow your open-source stack to remain a compliance blind spot. The right oversight today is tomorrow’s trust capital. Elevate your standing: turn OSS compliance from a risk into operational, boardroom, and market confidence-before the next question or incident ever lands.
Frequently Asked Questions
Who is responsible for open-source library risk under NIS 2, and does open-source software count as a supplier?
Under the NIS 2 Directive, your board and executive management are directly responsible for addressing open-source library risk-regardless of whether a library is “free” or commercial. Open-source software is unequivocally treated as a third-party supplier from a regulatory perspective: if you don’t control and develop the code in-house, it’s part of your digital supply chain. This means your organisation is expected to place open-source components under the same governance-approval, risk monitoring, owner assignment, and evidence requirements-as any commercial or managed service. The board is now accountable for high-level oversight, including regular reviews of SBOMs (Software Bill of Materials), risk registers, and policy sign-offs, and must be able to demonstrate this compliance during regulatory checks and audits.
Table: Who Owns Supplier Risk under NIS 2?
| Dependency Type | NIS 2 Supplier? | Accountable Owner |
|---|---|---|
| Commercial Vendor | Yes | Board/Executive Sponsor |
| Managed Services | Yes | Board/Executive Sponsor |
| Open-source Library | Yes | Board/Executive Sponsor |
| In-house Code | No (internal) | IT / System Owner |
Every piece of open-source code you use is now a supply chain exposure-expect scrutiny from both regulators and insurers as if it were a paid third-party.
What are the audit risks of neglecting open-source supply chain management?
If you overlook open-source as a formal supply chain issue, shadow dependencies and untracked code proliferate-creating invisible audit liabilities. These include deeply nested libraries, direct downloads, or unchecked updates that evade central records. Audits quickly expose these blind spots: you may fail to produce a complete SBOM, lack clear ownership of dependencies, or show patch lags and missing documentation. Regulatory findings can lead to failed certifications, escalated insurance premiums, and even fines-especially if an untracked or unpatched open-source component triggers an incident, as high-profile vulnerabilities like Log4Shell or XZ Utils recently demonstrated.
Table: Critical Audit Gaps-OSS Oversight
| Audit Finding | Common Gap Exposed | Possible Repercussion | |
|---|---|---|---|
| Incomplete SBOM | Missing open-source inventory | Loss of certification; audit fail | |
| No named owner | No one assigned to patch/check OSS | Regulatory fine; insurance void | |
| Patch delay logs | Late/missing patch documentation | Incident liability; board exposure | |
| Poor risk trail | No incident or review evidence | Heightened oversight, reputational risk | , Anchore on NIS2 & SBOM,* |
How does NIS 2 reshape open-source due diligence compared to commercial suppliers?
NIS 2 does not distinguish between open-source and paid vendors: every open-source component must go through the same supplier lifecycle as any commercial product. This includes:
- Onboarding: Mandatory checks on provenance, licencing, and maintainer trustworthiness.
- Security vetting: Risk and vulnerability reviews (actively maintained, security disclosures, CVE tracking).
- Continuous monitoring: Automation to keep your SBOM live and dynamic, including for all transitive (nested) dependencies.
- Assignment: Every OSS element must have a named business owner and reviewer.
- Evidence and approval: Records of review, onboarding, and sign-off must be auditable and board-visible.
Failing to treat OSS with this level of diligence means critical gaps-when an audit or incident hits, “we didn’t know” is no longer a viable defence.
Table: NIS 2 Control Parity-OSS vs. Commercial
| Control/Process | OSS | Commercial Vendor |
|---|---|---|
| Licence/Provenance Review | Required | Required |
| Security Assessment | Required | Required |
| SBOM Inclusion | Required | Required |
| Named Owner/Reviewer | Required | Required |
| Ongoing Monitoring | Required | Required |
What documentation and evidence does NIS 2 require for open-source oversight?
NIS 2 and ISO 27001 expect you to create a living, audit-ready record of open-source management-centralised, up-to-date, and role-mapped:
- SBOM (Software Bill of Materials): Every direct and transitive OSS component, licence, version, and owner mapped.
- Vulnerability and risk logs: Automated records linking every OSS to risk status, flags for every open vulnerability (e.g., CVEs), and actions taken, time-stamped and assigned.
- Remediation and patch history: Log all responses to vulnerabilities, including patch tickets, board sign-offs, and staff acknowledgements.
- Ownership registry: Each OSS named with a business/board owner and reviewer, and a sign-off/audit trail for each control point.
- Change logs and policy records: Document every policy change, incident, training event, or board review, with full attribution and date.
A paper trail or isolated spreadsheet no longer passes muster: your ISMS needs to generate and export this evidence as a single, cohesive record-ready for audit at any moment.
Table: OSS Evidence Examples
| Document Type | Owner/Signer | Example Output | Regulatory Anchor |
|---|---|---|---|
| SBOM Component | Sec Lead/Board | Full entry, sign-off | NIS 2 Art. 21, ISO A5.21 |
| Vulnerability Log | IT/Ops Owner | CVE record, patch status | ISO A8.8, NIS 2 21.2(e) |
| Approval Trail | Board Sponsor | Review & risk sign-off | NIS 2, Board Mandate |
How does automation and dashboarding reduce NIS 2 compliance fatigue for open-source?
Automation is essential: modern dashboard-driven ISMS platforms eliminate the manual, repetitive drudgery (and missed detail) that comes with open-source supply chain oversight. Automated tools should:
- Route new dependencies and risks: Ownership is auto-assigned for review, escalation, and documentation-no dependency goes “unowned.”
- Visualise risk instantly: Dashboards flag overdue patches, missing sign-offs, or unowned OSS, driving actionable focus.
- Generate audit packets: One-click export of all relevant records-owner lists, evidence chains, SBOMs-means audits start ready, not in panic.
- Create a continuous feedback loop: Policy, user acknowledgment, and incident patterns feed continual improvement and adaptation.
- Show real board visibility: Boards access real-time, role-based dashboards, so supply chain and OSS risk never become afterthoughts.
With automation, open-source risk management is no longer back-office firefighting-it's a transparent, continuous pillar of business resilience.
What does a mature, NIS 2 and ISO 27001–aligned open-source workflow look like in an ISMS?
In a modern ISMS, open-source risk management isn’t an exception or a special project-it’s fully integrated into daily operations, audit prep, and board review:
- Onboarding: Every new OSS component triggers licence and risk review, feeding directly (and automatically) into the SBOM and risk registers.
- Ownership and monitoring: Each component mapped to an accountable owner; all vulnerabilities or policy deviations escalate for immediate action.
- Automated compliance chain: All reviews, patch events, policy updates, and incidents time-stamped, linked, and ready for export.
- Board governance: Dashboards surface real-time, actionable risk and approval evidence for board review-no last-minute paper chase needed.
Table: End-to-End OSS Compliance Traceability
| Workflow Step | Event/Action | ISO/NIS 2 Reference | Evidence Example |
|---|---|---|---|
| Add OSS | New dependency discovered | ISO A5.21; NIS 2 Art.21 | SBOM & licence review |
| Assign Owner | Approval/Onboarding | ISO A5.2; NIS 2 21.2 | Reviewer sign-off |
| Patch Vulnerability | CVE disclosed or updated | ISO A8.8; NIS 2 21.2(e) | Patch log, ticketing |
| Board Review/Audit | Scheduled/risk event | ISO 9.3/10.1; NIS 2 Bd | Audit export, summary |
Turn open-source from a weak link to a board-certified strength
NIS 2 and ISO 27001 make open-source risk a strategic, executive-level responsibility-no longer just IT’s “problem.” Automate your SBOM, assign ownership for every component, evidence every decision, and bring risk out of the shadows. The organisations that treat OSS with rigour, not indifference, are the ones that win audits, lower incident costs, and strengthen board and customer trust.
Ready to bring your OSS supply chain risk into clear focus? Embed open-source diligence into your ISMS, empower your leadership team, and let audit readiness become your competitive shield.
For practical toolkits and further guidance, see ENISA’s Open Source Guidelines,, and ISMS.online’s NIS 2 resource library.
