Security Engineer Intern (Summer 2026)

Available location(s): Lisbon, Portugal

About Cloudflare's Security Team

Security is at the heart of Cloudflare’s mission to help build a better Internet. Anytime we push code, it automatically affects the millions of Internet properties (powering websites, remote teams, APIs, mobile apps, etc.) running on our global network. Cloudflare's network is one of the largest in the world, spanning over 330 cities in more than 125 countries, and operating within 50 milliseconds of 95% of the Internet-connected population.

Security Engineering spans across the Cyber Defense & Engineering and CloudforceOne Threat Intelligence & Research teams within the Security group under our Chief Security Officer. Security at Cloudflare ensures that this massive flow of traffic remains secure and resilient against evolving threats. While our core engineering teams build the software that handles traffic, our security engineers build the systems that protect it. Technologies we use to defend the Internet include Go, Rust, Python, and C/C++.

About the Internship Program

The ideal Security Engineering intern is passionate about making the Internet a more secure place. You will work alongside experienced security engineers to identify vulnerabilities, harden our infrastructure, and build tools that protect billions of Internet users. We are looking for interns who are curious, proactive, and able to approach problems with a "security-first" mindset. This is a unique opportunity for engineers who want to learn how to defend systems at a scale that few other companies can offer.

What would you do as a Cloudflare intern?

• Ship and deliver security-focused projects over 12-16 weeks with autonomy and support.
• Work cross-functionally with Product, Infrastructure, and Engineering teams to integrate security into every stage of the development lifecycle.
• Work closely with a mentor to guide you through the internship, develop your security expertise, and help with career goals.
• Build your network across the company through our various in and out of office socials, networking programs, Employee Resource Group (ERG) programs, and Activity Groups.
• Present your security project to the entire company at the end of the internship.
• Connect and learn from our executives and leadership team including our co-founders.
• Write for our Cloudflare blog (e.g., documenting a new security tool or a vulnerability research finding) and be featured on Cloudflare.tv sessions.

You can check out our internship blogs to learn more about our program and hear directly from our past interns.

Examples of desirable skills, knowledge and experience