Staff Application Security Engineer

Brex

5d•$240,000 - $300,000•Hybrid

About The Position

Brex is seeking a Staff Application Security Engineer to define the technical vision and long-term security architecture for the Brex platform. This role involves leading the Application Security team, driving the strategy for secure product lifecycles and vulnerability management. It requires cross-functional collaboration across the engineering organization to integrate security into development pipelines. The ideal candidate will have a strong background in penetration testing, experience identifying and documenting vulnerabilities, and the ability to clearly communicate risks. This position will also focus on securing AI implementations, identifying attack vectors in agentic features, and hardening distributed LLM architectures, while mentoring team members and raising the technical bar for the organization.

Requirements

8+ years of experience in Application Security, Product Security, or software engineering with a primary focus on offensive and defensive application security.
Proven track record of technical leadership and team mentorship on complex, multi-quarter security engineering initiatives in a fast-paced environment.
Deep proficiency and technical expertise in AI security, including hands-on experience securing agentic architectures, LLM gateways, and evaluating adversarial AI vectors.
Strong systems-thinking capabilities with extensive experience defining secure product development lifecycles, threat modeling complex topologies, and cloud-native container security (AWS, Kubernetes).
Proficiency in Python, Go, or similar languages to architect internal tooling, pipeline automation, and advanced detection/scanning engines.
Exceptional written and verbal communication skills, with a demonstrated ability to navigate ambiguity, influence technical leaders, and manage up and out across EPD organizations.

Nice To Haves

Experience with Kotlin, gRPC, GraphQL, Kubernetes
Previous experience in building and scaling security teams
Experience with securing distributed systems in AWS and cloud environments
Contributions to the wider technical community — open source, public research, CTF participation, blogging, CVEs, or presentations
Experience submitting to bug bounty or responsible disclosure programs
Published AI security research or contributions to AI security frameworks

Responsibilities

Lead the technical vision and strategic roadmap for the Application Security team, aligning security objectives with Brex's enterprise growth and high-velocity engineering metrics.
Establish technical standards and secure defaults across the entire engineering organization, fostering a culture of collaborative security excellence and bridging product platforms, infra, and trust.
Architect and secure novel AI/ML and agentic workflows, applying cutting-edge practices to mitigate risks such as prompt injection, model manipulation, and data poisoning.
Mentor and coach engineers within the team and across the broader organization, guiding technical growth, helping individuals level up their security expertise, and accelerating team delivery.
Drive proactive vulnerability discovery and offensive security testing strategies, executing complex attack chains to demonstrate business impact and prioritize cross-functional remediation.
Partner with Product Platform, Cloud Infrastructure, and Data engineering teams to ensure core primitives, APIs, and microservices are secure by default from design to deployment.