Senior Security Engineer

Lumos builds an autonomous identity platform that connects applications, identities, and data. The Senior Security Engineer will build security foundations for the platform, lead security projects and reviews, improve least-privilege access, and help customers and internal teams address security risks.

Responsibilities:

• Design and ship core security platform systems in the Lumos codebase, such as request context propagation across services, scoped API tokens, our authorization service, and decoupling authentication from synced identities
• Lead multi-sprint security projects end to end, coordinating with engineers on other teams to get them delivered
• Run security architecture reviews and threat models for new products (for example our MCP Governance gateway and on-device policy checks) before they scale, and turn findings into tracked, prioritized work
• Drive least-privilege access to our own production systems (databases, data pipelines, AWS IAM, secrets)
• Triage, route, and fix vulnerabilities from pentests, cloud assessments, and dependency scanning, and coordinate retests
• Take part in security oncall and incident response, and help answer security questions from customers and prospects

Requirements:

• 5+ years of software engineering experience, with at least 3 focused on security (application, product, or platform security)
• A track record of designing, shipping, and operating production security systems, not only reviewing them
• Strong backend skills
• Clear written communication. You can explain a risk and a trade-off to engineers, PMs, and customers alike
• Hands-on experience with threat modeling, secure design review, and finding and fixing vulnerabilities in a real codebase
• Experience securing cloud infrastructure on AWS (equivalent GCP or Azure experience considered), including IAM and Infrastructure as Code
• Python and TypeScript are a strong plus
• identity protocols (OAuth 2.0, OIDC, SAML, SCIM), policy engines (OPA, Zanzibar-style models, Cedar), SOC 2 or ISO 27001 environments, general background in IAM, and/or growth-stage startup experience