NIS2 compliance: What zero-day attacks reveal about EU readiness in 2025

In today’s Brussels briefing, regulators reiterated that NIS2 compliance is not a paperwork exercise but an operational duty. That message lands amid fresh zero-day headlines: an email/calendar-borne exploit campaign abusing .ics files, and a rapidly weaponized enterprise vulnerability used for data theft. For EU organizations, these cases underline exactly what NIS2 was designed to fix—supply chain exposure, insecure document handling, and late reporting that blindsides regulators and customers.

I’ve spoken with CISOs this quarter who described calendar invites as “the new macro,” and vendor patches as “24-hour sprints.” With EU regulations tightening, and GDPR and NIS2 now overlapping on incident handling, the lesson is clear: control data, control uploads, and assume adversaries will land in your inbox.

Why zero-days are a NIS2 compliance issue

Two patterns from recent attacks have direct implications for NIS2:

• Abuse of trusted file types: ICS calendar invites and office documents ride past user suspicion, making “secure document uploads” controls and content sanitization mandatory for critical functions.
• Exploit-to-breach speed: Ransom and data-theft groups operationalize vendor CVEs within days, compressing your window to detect, patch, and report under NIS2 timelines.
• Supply-chain risk: Email gateways, collaboration suites, and third-party plugins extend your attack surface—exactly the “essential” and “important” vendor dependencies NIS2 expects you to govern.

Under NIS2, essential and important entities must be able to: identify critical assets, apply risk-based technical and organizational measures, prove vendor due diligence, and meet strict incident reporting milestones (early warning within 24 hours, notification within 72 hours, and a final report within one month). Failure invites fines up to €10 million or 2% of global turnover, plus potential management liability.

GDPR vs NIS2: what changes for CISOs, DPOs, and legal

Many teams still treat NIS2 as “GDPR but for networks.” It isn’t. Here’s how obligations differ:

Topic	GDPR	NIS2
Primary focus	Personal data protection and privacy rights	Service continuity and resilience of essential/important entities
Who is covered	Any controller/processor handling EU personal data	Sector-based entities (energy, finance, health, digital infra, etc.) and size criteria, including key suppliers
Incident reporting	Notify DPA within 72 hours for personal data breaches	Early warning in 24h, incident notification in 72h, final report in 1 month for significant incidents
Security measures	Appropriate technical/organizational measures to protect personal data	Risk management, supply-chain security, vulnerability handling, business continuity, crypto, MFA, logging
Fines	Up to 4% global turnover or €20m	Up to 2% global turnover or €10m, plus management accountability and audits
Audits/enforcement	Data Protection Authorities	National competent authorities, sector regulators, and CSIRTs with on-site inspections
Vendor management	Data processing agreements; transfer mechanisms	Proof of supplier cyber controls; contractual and technical assurance for critical suppliers

Practical NIS2 compliance checklist for Q4 2025 audits

• Map “essential services” and critical assets; assign accountable owners.
• Implement vulnerability management with a 72-hour remediation triage for active exploits.
• Enforce secure document handling: quarantine, sanitize, and scan ICS/PDF/DOC/XLS uploads and email attachments.
• Apply multi-factor authentication, least privilege, and network segmentation to high-impact systems.
• Centralize logs and telemetry; enable 12–18 months retention for forensics.
• Test incident reporting drill: produce a 24-hour early warning and a 72-hour regulator narrative.
• Verify supplier risk: collect evidence of patch SLAs, security audits, and breach notification clauses.
• Train staff on social engineering involving calendar invites and collaboration tools.
• Establish data minimization and AI anonymizer workflows before sharing files internally or with LLMs.
• Run tabletop exercises that include ransomware plus vendor outage scenarios.

Handling documents and AI safely: anonymization and secure uploads

Zero-days increasingly enter through everyday files—emails with ICS invites, PDFs, and spreadsheets. Two safeguards reduce both breach and regulatory risk:

• Pre-share redaction: Strip personal data, identifiers, and confidential fields using an anonymizer tool that supports structured and unstructured formats.
• Controlled ingestion: Use a secure document reader that opens files in a hardened, policy-controlled environment—no macros, no live links, and auditable access.

Professionals avoid risk by using Cyrolo’s anonymizer before files move to shared drives or AI workflows. Try our secure document reader today — no sensitive data leaks.

Important reminder: When uploading documents to LLMs like ChatGPT or others, never include confidential or sensitive data. The best practice is to use www.cyrolo.eu — a secure platform where PDF, DOC, JPG, and other files can be safely uploaded.

Incident reporting timelines and supply-chain due diligence under NIS2

Expect regulators to test three intertwined capabilities during inspections and security audits:

1. Detection and triage: Demonstrate that exploited CVEs or malicious attachments are detected quickly, with severity assessed and business impact estimated.
2. Reporting discipline: Produce a 24-hour early warning (initial facts, suspected cause, cross-border effects), a 72-hour notification (confirmed impact, mitigations), and a comprehensive final report within one month (root cause, lessons learned, future prevention).
3. Supplier assurance: Evidence that your vendors patch critical flaws swiftly; show test results, patch timelines, and alternative controls if patching is delayed.

A CISO I interviewed last week summed it up: “NIS2 is the first time my board asks how fast our partners patch—not just us.” That’s the shift.

Sector snapshots: how teams are adapting

• Bank/fintech: A European bank blocked ICS attachments at the gateway and rerouted calendar invites through a sandbox and secure document uploads process. Result: a near-miss phishing wave was contained with zero lateral movement.
• Hospital: A regional hospital anonymized discharge summaries before sharing with analytics vendors via an AI anonymizer, eliminating personal data exposure in third-party environments and easing DPIA work.
• Law firm: Litigation teams switched to a controlled reader for discovery files, blocking macros and external calls. Board was briefed on NIS2 timelines alongside GDPR breach thresholds to harmonize response plans.

EU vs US: different levers, same urgency

The EU pairs prescriptive security measures (NIS2) with privacy rights (GDPR). In the US, sectoral rules and disclosure regimes (e.g., SEC incident disclosures, state breach laws, upcoming CIRCIA) push transparency but often leave technical control choices to firms. For multinationals, the safest approach blends EU-grade controls—vendor due diligence, strict timelines, encryption, and MFA—across all operations.

One blind spot I still see: AI workflows. Teams paste sensitive case files into general-purpose LLMs, blurring confidentiality and export control lines. Redaction and compartmentalized readers are now table stakes for cross-jurisdiction data protection.

Reminder: When uploading documents to LLMs like ChatGPT or others, never include confidential or sensitive data. The best practice is to use www.cyrolo.eu — a secure platform where PDF, DOC, JPG, and other files can be safely uploaded.

FAQs: your top NIS2 compliance questions

What is the fastest way to show NIS2 readiness to regulators?

Start with evidence: risk register for essential services, recent vulnerability handling (including zero-days), incident reporting playbooks with timestamps, and supplier patch SLAs. Add artifacts from a secure document uploads workflow and anonymization processes for personal data.

How does NIS2 interact with GDPR during a privacy breach?

If personal data is impacted, GDPR’s 72-hour breach notification applies alongside NIS2’s early warning and subsequent reports. Legal and security teams should run a unified response that meets both regimes. Redaction and an AI anonymizer can reduce personal data exposure during triage and evidence sharing.

Do small suppliers need to comply with NIS2?

Yes—if they are material to an essential/important entity’s service. Prime contractors must demonstrate supplier due diligence. Expect requests for audit evidence, patch timelines, and incident notice commitments.

What are the penalties for missing NIS2 reporting deadlines?

National authorities can levy fines up to €10 million or 2% of global turnover for essential/important entities, impose corrective measures, and, in severe cases, hold management accountable.

Are email/calendar attachments still a major threat?

Yes. Attackers now weaponize “routine” formats like ICS invites and PDFs. Gateway filters, sandboxing, and a secure document reader materially reduce risk.

Conclusion: get to NIS2 compliance before regulators do

The latest zero-day campaigns underscore why NIS2 compliance is a business resilience goal, not just a legal checkbox. Prioritize rapid patching, supplier assurance, and safe document handling. Reduce breach blast radius with pre-share redaction via an anonymizer tool, and confine risky files to a secure document reader. Move now, and you’ll be ready for inspections, audits, and the next exploit wave—on your terms.