Offensive Security Engineer (CyberSecurity) in London

This role is ideal for those who thrive in dynamic environments, where creativity, technical depth, and a passion for security converge to solve unprecedented challenges.

• 7+ years of offensive security experience, with a track record of identifying and exploiting subtle vulnerabilities in complex systems—or equivalent expertise demonstrated through exceptional achievements.
• Deep knowledge of AI/ML security risks, including prompt injection, data leakage, model manipulation, and abuses of dynamic UI components.
• Hands-on experience assessing modern technology stacks, such as:
• Custom Kubernetes deployments and containerized environments.
• Cloud-native architectures (AWS, GCP, or Azure).
• CI/CD pipelines and GitHub security best practices.
• MacOS/Linux internals and Python/React-based applications.
• Data science toolchains and AI/ML infrastructure.
• A builder’s mindset: The ability to write robust tools, automate offensive workflows, and contribute to defensive solutions in complex codebases.
• Strong intuition for trust boundaries and risk assessment in fast-moving, high-stakes environments.
• Outstanding communication skills, with the ability to distill technical nuances into compelling narratives that drive change.
• A collaborative spirit, eager to work alongside engineers, researchers, and product teams to embed security into every phase of development.
• (Desirable) Background in AI, data science, or related fields, with an understanding of how security intersects with model behavior and system design.
• (Desirable) Experience in high-growth startups or research-driven organizations, where agility and innovation are paramount.
• (Desirable) Expertise in adjacent disciplines, such as software engineering, detection engineering, SRE, or security architecture.

What the job involves:

At Mistral AI, we’re pushing the boundaries of what’s possible with agentic systems—building products like Mistral Studio and Mistral Vibe that redefine how users interact with AI. As a Security Researcher, you’ll play a pivotal role in safeguarding these innovations by anticipating, identifying, and mitigating risks before they materialize. This isn’t just about finding vulnerabilities; it’s about shaping the future of secure AI by embedding an attacker’s mindset into everything we build.

You’ll work at the intersection of offensive security, AI safety, and product development, collaborating with cross-functional teams to harden our systems against evolving threats. Your expertise will directly influence how we design, deploy, and protect our most critical assets — ensuring our agents remain resilient, trustworthy, and ahead of adversaries.

• Proactively hunt for vulnerabilities in the interactions between our agentic applications, cloud infrastructure, and foundational models, with a focus on realistic, high-impact attack vectors.
• Design and execute red and purple team exercises, simulating sophisticated adversarial scenarios to stress-test our defenses and refine our detection capabilities.
• Partner with defensive teams to translate offensive insights into actionable improvements, from detection engineering to incident response.
• Conduct in-depth penetration testing across our product suite, including AI-driven workflows, custom infrastructure, and user-facing interfaces.
• Build and automate offensive tooling to scale your impact, leveraging cutting-edge techniques to stay ahead of emerging threats.
• Communicate findings with clarity and conviction, ensuring technical and non-technical stakeholders understand risks and prioritise mitigations effectively.
• Shape Mistral AI’s security strategy by contributing attacker-informed perspectives to threat modeling, risk assessment, and architectural decisions.