Security Software Engineer, Open Source Frameworks in London

About Vercel: Vercel is the agentic infrastructure company. We free people and agents to ship what’s next. For more than a decade, Vercel has shaped how the web is built. As the team behind Next.js, v0, and AI SDK, we create products that help builders move from idea to production with speed, security, and exceptional developer experience. Now, software is entering a new era, and the next generation of products will not just be used by people. They will be built, extended, and operated by agents. We are building the platform for that future, trusted by companies like OpenAI, PayPal, Ramp, Supreme, and millions of developers worldwide.

About the role: Vercel builds and maintains a broad portfolio of open source projects that power the modern web, running in millions of applications. Your primary focus will be Turborepo, Nuxt, Svelte/SvelteKit, SWR, Workflow, and Nitro. A single structural fix at the framework level protects every one of those applications at once, which makes this one of the highest-leverage security roles at the company. We're looking for a security engineer who loves finding a whole class of vulnerability and eliminating it in one move, not someone who's satisfied filing one bug at a time. You'll run deep security assessments of framework internals (routing, middleware, caching, server actions, the build pipeline), find the systemic patterns that produce entire families of bugs, and drive the framework-level fixes and design changes that remove them permanently. You'll also own how these projects handle externally reported vulnerabilities, coordinated disclosure, and CVEs, working directly with maintainers and the open source security community. This includes hands-on ownership of Vercel's open source bug bounty program for these projects: triaging incoming reports, validating and reproducing findings, and driving fixes with the right maintainers.

What you will do:

• Hunt for vulnerability classes, not individual bugs: Run deep security assessments of framework internals (routing, middleware, caching, data fetching, server actions/RSC boundaries, build tooling) to find the systemic design patterns that produce whole families of issues.
• Drive root-cause framework fixes: Push design changes upstream that eliminate a category of vulnerability across every application built on the framework, rather than patching individual instances as they're reported.
• Own vulnerability disclosure and CVEs: Triage security reports from the community and researchers across Turborepo, Nuxt, Svelte/SvelteKit, SWR, Workflow, Nitro, and other maintained OSS projects. Coordinate embargoed fixes, write and publish advisories, and manage the CVE/CNA process end to end.
• Run the OSS bug bounty program for these projects: Own triage and validation of incoming reports to Vercel's open source bug bounty program for Turborepo, Nuxt, Svelte/SvelteKit, SWR, Workflow, and Nitro. Reproduce findings, assess severity, and coordinate fixes with the right maintainers and researchers.
• Get security into design early: Partner with framework maintainers and core teams during RFCs and design review, so new features ship with security considered from the first draft, not bolted on after a report comes in.
• Build preventive tooling: Contribute linters, codemods, and CI checks that catch regressions of previously-fixed vulnerability classes before they land again.
• Own supply chain security for these projects: Harden how dependencies, releases, and published packages for Turborepo, Nuxt, Svelte/SvelteKit, SWR, Workflow, and Nitro are built, signed, and distributed.
• Work with the community, not around it: Engage directly with maintainers, contributors, and external researchers as peers. Bring pragmatic security recommendations to project discussions in a way that respects how these projects actually get built.

About you:

• You've actually used or broken these frameworks: You've built real things with Turborepo, Nuxt, Svelte/SvelteKit, SWR, Workflow, or Nitro (or closely comparable projects), or you've found and reported security issues in them.
• You have a deep appreciation and respect for open source work: You understand that these are community projects with maintainers, contributors, and users who care deeply about them.
• 4+ years in security engineering, ideally with real hands-on open source contribution experience.
• You're energized by root cause, not remediation count: Finding the one design flaw that kills fifty potential bugs is more satisfying to you than closing fifty tickets one at a time.
• You can read framework internals, not just application code: Strong JavaScript/TypeScript fundamentals and genuine familiarity with how modern meta-frameworks work under the hood.
• Pragmatic, not theoretical: You can weigh real-world risk against maintainer and community bandwidth, and land on security improvements that actually ship.
• Vulnerability research chops: Experience with structured security assessment methodology and coordinated/responsible disclosure processes.
• Clear communicator: You can explain a vulnerability, a tradeoff, or a design recommendation clearly to maintainers, contributors, and non-security engineers alike.
• Comfortable operating in public: You're used to working transparently with external researchers, maintainers, and the community.

Bonus if you have:

• CVE credits or published security research, especially in JavaScript frameworks or the Node ecosystem.
• Maintained or heavily contributed to a widely used open source project.
• Experience with supply chain security tooling.
• Thought about how increasing AI-agent-authored contributions change the risk model for open source maintenance.
• Run or triaged for a bug bounty / vulnerability disclosure program before, ideally for open source projects.

Benefits:

• Competitive compensation package, including equity.
• Inclusive Healthcare Package.
• Learn and Grow - we provide mentorship and send you to events that help you build your network and skills.
• Flexible Time Off.
• We will provide you the gear you need to do your role, and a WFH budget for you to outfit your space as needed.

Vercel is committed to fostering and empowering an inclusive community within our organization. We do not discriminate on the basis of race, religion, color, gender expression or identity, sexual orientation, national origin, citizenship, age, marital status, veteran status, disability status, or any other characteristic protected by law. Vercel encourages everyone to apply for our available positions, even if they don't necessarily check every box on the job description.