Head of Security Reliability

About Nebius: Nebius is leading a new era in cloud infrastructure for the global AI economy. We are building a full-stack AI cloud platform that supports developers and enterprises from data and model training through to production deployment, without the cost and complexity of building large in-house AI/ML infrastructure. Built by engineers, for engineers. From large-scale GPU orchestration to inference optimization, we own the hard problems across compute, storage, networking and applied AI. Listed on Nasdaq (NBIS) and headquartered in Amsterdam, we have a global footprint with R&D hubs across Europe, the UK, North America and Israel. Our team of 1,500+ includes hundreds of engineers with deep expertise across hardware, software and AI R&D. About the role   Nebius is looking for a Head of Security Reliability to establish and lead the Security Reliability pillar. Reporting directly to the CISO, this leader will be accountable for the ongoing effectiveness, resilience, and operational maturity of Nebius security products after implementation.   The role ensures that security platforms remain properly configured, maintained, integrated, monitored, adopted, and optimized to deliver measurable risk reduction. It also owns Nebius's Third-Party Risk Management (TPRM) program and the security-review process for new products, services, and technologies introduced across the company.   This is a hands-on leadership position for someone who combines security expertise, operational discipline, vendor-management experience, and a strong product mindset. The role partners closely with Security, IT, Engineering, Product, Procurement, Legal, Privacy, Compliance, and business stakeholders.   Key responsibilities   Security product reliability and lifecycle ownership   Own security products and platforms after implementation, from operational handover through optimization, renewal, replacement, or retirement.   Ensure security tools are correctly configured, maintained, integrated, monitored, and aligned with Nebius's risk profile and technical environment.   Define ownership, service levels, operating procedures, support models, and escalation paths for every security platform.   Monitor platform availability, data quality, control coverage, integration health, licensing, capacity, and performance.   Establish disciplined processes for upgrades, configuration changes, testing, exception management, and end-of-life planning.   Continuously assess whether security products deliver their intended outcomes, and improve utilization, coverage, automation, and return on investment.   Reduce overlapping capabilities, configuration drift, operational gaps, and underused tooling across the security stack.   Manage vendor performance, technical escalations, product-roadmap discussions, renewals, and service reviews.   Ensure newly implemented security products transition into operations with clear documentation, ownership, monitoring, and success criteria.   Security configuration and control assurance   Define and maintain secure configuration baselines for security platforms.   Establish continuous control-health monitoring to identify disabled, degraded, misconfigured, or incomplete controls.   Validate that integrations and telemetry remain complete, accurate, and reliable as Nebius's environment evolves.   Coordinate remediation of control gaps with Security, IT, Engineering, and platform owners.   Maintain evidence demonstrating the operational effectiveness of security controls for audits, certifications, and customer-assurance activities.   Security reviews for new products and technologies   Lead the security-review process for new products, services, platforms, and technologies being introduced at Nebius.   Engage early with Product, Engineering, IT, Procurement, and business teams to identify security requirements and risks.   Review proposed solutions across architecture, identity and access, data protection, logging, integrations, cloud configuration, resilience, and third-party dependencies.   Provide pragmatic, risk-based recommendations that enable teams to move forward securely.   Define approval criteria and ensure identified risks have clear owners, remediation plans, compensating controls, or formally documented acceptance.   Establish reusable standards, questionnaires, patterns, and workflows to improve review consistency and turnaround time.   Ensure approved products transition into the appropriate operational, monitoring, and risk-management processes.   Leadership and governance   Build, lead, and develop a high-performing Security Reliability team.   Define the pillar's strategy, roadmap, operating model, priorities, budget, and success measures.   Create clear accountability across internal teams and external ser