Senior Security Engineer, Product & Infrastructure

ABOUT the company

The company is a financial technology company building products and APIs for the stablecoin economy. We build on open infrastructure, global money, and internet capital markets to deliver better financial services to businesses, individuals, and developers.

Our products span the company’s mission: the company Multisig helps teams secure and manage assets on Solana; Altitude gives businesses a global account to run their financial operations; and Fuse brings stablecoins and tokenized assets to personal finance.

More than 450 teams use the company Multisig to secure over $10 billion in value. Our investors include Haun Ventures, Multicoin Capital, Electric Capital, Coinbase Ventures, Toly, Mert, and others.

THE ROLE

You’ll own product and infrastructure security across the company, working closely with our Head of Security, CTO, and engineering leads across Multisig, Altitude, Fuse, and the infrastructure that powers them. That means being in the room when systems are designed, reviewing code before it ships, and driving every finding to verified closure.

This is a hands-on role. You’ll read code, write threat models, and build the tooling and standards that make the secure path the default as engineering grows. We’re looking for a senior practitioner who can tell engineers what to fix and why, and hold the line on what matters without slowing the team down.

WHAT YOU’LL OWN

DESIGN & CODE REVIEW

• Join product and engineering calls as the security reviewer, raising concerns while designs are still cheap to change

• Lead threat modeling and security design reviews for new products, features, and infrastructure changes

• Perform hands-on secure code review across backend services, APIs, frontends, and Solana programs, with a focus on authentication, authorization, and access control

VULNERABILITY MANAGEMENT

• Own the full lifecycle for findings from audits, pentests, code scanning, and bug bounty: triage, prioritization, remediation tracking, and fix verification

• Set severity and SLA standards, and hold the team to them

• Run bug bounty intake, validate external reports against source, coordinate with audit partners, and scope internal assessments

SECURE SDLC & INFRASTRUCTURE

• Tune and extend SAST, dependency, secrets, and container scanning in CI/CD so engineers trust the signal

• Review IAM, network controls, encryption, and secrets management across our cloud environments, including API key ownership, permissions, and rotation

• Assess what internal AI tools, MCP integrations, and agents can reach in production, and scope their access to what they need

• Define product security standards, review checklists, and developer guidance that scale with the team

YOU MIGHT BE RIGHT FOR THIS IF

• You’ve been the senior security partner to engineering leadership, and teams sought out your review instead of routing around it

• You find business logic, authorization, and race condition bugs by reading code, and you know where scanners go blind

• You use LLMs and agents to cover far more code than one person could, and you know where the models miss

• You rank findings by what an attacker could actually do with them, and your write-ups tell engineers exactly what to change

• You’ve worked where security failures carry direct financial impact: fintech, crypto, payments, or stablecoins

• You’ve built a security function early, when the process and tooling still needed to be defined

• You pick your battles, and engineers ship faster with you in the room

REQUIREMENTS

• 8+ years in product security, application security, or security engineering, built on a software engineering foundation

• Ownership of threat modeling and architecture review for complex financial or distributed systems, with the standing to shape design decisions

• A track record of finding critical, non-obvious vulnerabilities in large production codebases (TypeScript, Rust, Go, or Python), including through LLM and agent-based review workflows you built and ran

• Experience building and running a vulnerability management program or bug bounty end to end, including the CI/CD scanning that feeds it

• Deep expertise in IAM, secrets management, network controls, and container security on AWS or a comparable provider

• Strong written communication and the judgment to work independently

• Experience reviewing Solana programs (Rust/Anchor) or working at an audit firm, cryptography and key management (HSMs, MPC, PKI), offensive testing across web and mobile, red teaming AI systems, or supporting SOC 2 from the product side is a plus.

WHY THIS MIGHT BE INTERESTING

Most product security roles sit downstream of engineering, reviewing what’s already been decided. This one sits in the room. You’ll shape how a self-custody platform, a business account, a consumer app, and the infrastructure under all of them get built, across Solana programs and traditional backend services alike.

The stakes are concrete: a missed authorization check here moves money. You’ll work directly with our Head of Security and CTO, with the ownership to build the product security program while operating it.

Small team, high standards. Learn more about our core values here [link for members]