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Third-Party Cyber Risk / Vendor incident coordination
Third-party cyber risk guide

Third-Party Cyber Incident Coordination

What should happen when a critical supplier has a cybersecurity incident?

Direct answer

Treat the supplier incident as a business dependency problem as well as a vendor issue. Establish affected services and data, create an internal incident owner, preserve available evidence and communications, confirm supplier contacts and notification facts, assess compensating controls and access changes, track recovery dependencies, and keep decisions and unknowns in one timeline.

External reference

National Institute of Standards and Technology (NIST) — SP 800-61 Rev. 3 — Incident Response Recommendations and Considerations for Cybersecurity Risk Management

Final April 2025. NIST integrates incident response into cybersecurity risk management and emphasizes preparation, response, recovery and learning across organisational dependencies.

Primary source →

Practical workflow

Step 1

Create internal ownership

Do not outsource accountability for impact assessment, business decisions, communications or recovery dependencies to the supplier.

Step 2

Establish confirmed scope

Separate supplier statements, internal observations, assumptions and unknowns about affected services, data, credentials and integrations.

Step 3

Reduce dependency risk

Where justified, rotate credentials, restrict integrations, apply compensating controls, change workflows or isolate affected interfaces.

Step 4

Preserve evidence and decisions

Retain notices, communications, logs, timestamps, changes, access decisions and internal impact assessments.

Step 5

Validate recovery and lessons

Confirm service restoration, residual risk, required remediation and whether vendor criticality, contract terms or architecture should change.

Relevant Cybatar sources

Claim boundary

Cybatar can structure incident, evidence, vendor and risk records, but it cannot determine a supplier’s undisclosed facts or replace contractual, regulatory, privacy, forensic or legal advice required for a specific incident.

These pages are Cybatar-authored third-party cyber risk and resilience guidance. NIST publications are used as external references. The mappings are not NIST validations, certifications, endorsements, legal opinions or statements that a supplier or deployment is secure.

Evidence