Senior GenAI Security Engineer

Lenstra; Paris; Hybrid; EUR 129,000 - 148,000; Full time

Benefits offered by this job

2 days home office per week

Hybrid work model

Job summary

Lenstra is seeking an Application Security expert to lead AI and cloud security across client environments, shaping policies and security controls from design to production. You will drive threat modeling, design reviews, and secure deployment of identity and access controls for on‑prem and cloud systems.

The role requires deep AWS security expertise, hands-on experience with LLMs, and fluent French and English communication. A hybrid work setup with 2 days of home office per week is offered.

Qualifications

• 5+ years of hands-on AppSec on modern cloud architectures.
• Deep AWS cloud security expertise.
• Solid grasp of LLM architecture, embeddings, vector databases, RAG and inference.
• Hands-on experience securing MCP servers, skills and agentic coding tools (e.g. Claude Code).
• Experience on OWASP Top 10 for LLMs and for Agentic Applications.
• Experience on SAML, OAuth2, OpenID Connect.
• Docker, Kubernetes security and image vulnerability scanning.
• IaC and automation: Terraform, Ansible, CloudFormation.
• Linux and networking (TCP/IP, UDP, HTTP/S, SSH).
• Strong coding skills in Python.
• Fluent French and English.

Responsibilities

• Be the go-to expert on AI and cloud application security, setting policies and best practices company-wide.
• Build and run controls to secure AI and agentic systems: sandboxes, guardrails, compliance checks, vulnerability management.
• Lead design reviews, threat modeling and architecture assessments before risks reach production.
• Deploy identity, authentication and access control (RBAC/ABAC) with the Core & Architecture team, on-prem and in the cloud.
• Help dev teams fix cloud and IaC findings, plug security tooling into CI/CD with low noise and zero slowdown, and track security KPIs.

Skills

AppSec expertise

Cloud security

Python programming

Threat modeling

Communicating in French and English

Security policy & governance

Tools

Docker

Kubernetes (EKS/ECS)

Terraform

CloudFormation

Job description

Lenstra was founded by engineers with a passion for Computer Science and a track record of delivering high-quality solutions. We work at the intersection of Cloud, DevOps, Data Platforms, AI and IT Security, helping top-tier clients in Banking, Insurance, Luxury and Tech solve their hardest technical challenges. Our approach is holistic: we build solutions that are as elegant as they are impactful.

The mission

You’ll join the Application Security team of one of our clients, working directly with its Director of AppSec. One goal: every AI project in the company ships secure, from design to production.

About the role

• You will be the go-to expert on AI and cloud application security, setting the policies and best practices teams follow company-wide.
• You will build and run the controls that secure AI and agentic systems: sandboxes, guardrails, compliance checks, vulnerability management.
• You will lead design reviews, threat modeling and architecture assessments before risks reach production.
• You will deploy agent identity, authentication and access control (RBAC/ABAC) with the Core & Architecture team, on-prem and in the cloud.
• You will help dev teams fix cloud and IaC findings, plug security tooling into CI/CD with low noise and zero slowdown, and track security KPIs.

What we look for

Mindset

• Builder, not auditor. You ship working tools, not just findings reports.
• Translator. You can explain a code vulnerability to a developer and a business risk to a director, in French and English.
• Ahead of the curve. You follow AI security research and adversarial TTPs, and bring them back to the job.

Must-haves

• 5+ years of hands-on AppSec on modern architectures: cloud, containers, serverless, APIs
• Deep cloud security expertise on AWS
• Solid grasp of LLM architecture, embeddings, vector databases, RAG and inference
• Hands-on experience securing MCP servers, skills and agentic coding tools (e.g. Claude Code)
• Experience on OWASP Top 10 for LLMs and for Agentic Applications
• Experience on SAML, OAuth2, OpenID Connect
• Docker, Kubernetes (EKS/ECS) security and image vulnerability scanning
• IaC and automation: Terraform, Ansible, CloudFormation
• Linux and networking (TCP/IP, UDP, HTTP/S, SSH)
• Strong coding skills in python
• Fluent French and English

Nice-to-haves

• Threat modelling or security audit experience
• MLOps pipelines and cloud AI services (SageMaker, Bedrock, Vertex AI, Azure ML)

What we offer

- TJM between 700 and 800, based on seniority and interview performance. No surprises.

- Remote policy: 2 days of home office per week

- A role at the frontier of a field most security teams are still figuring out.