Cybersecurity Specialist - Vulnerability & Threat Management

Applicants must be authorized to work for any employer in the country in which the role is being hired. We are unable to sponsor or take over sponsorship of an employment visa at this time.

Mark
43’s mission is to empower communities and their governments with new technologies that improve the safety and quality of life for all. We build powerful, scalable, and elegant software that sets a new standard for the tools upon which our first responders rely. Our users are diverse, and we are therefore committed to embracing diversity of thought and experience within our team.

We are looking for a Cybersecurity Specialist to join our team in Manchester.
You will be the security decision-maker on the ground in our Manchester office, owning vulnerability and threat management for an environment where the stakes are real. The software we build supports first responders, so the systems you protect help keep communities safe. The unique challenge of this role is breadth with depth: you will run a serious vulnerability and threat program while being the trusted, on-site presence who keeps the office and its people running, often making the call on your own and coordinating with a wider Cybersecurity team across time zones.

• Driven our vulnerability management program end to end: running scans across systems, networks, and applications, prioritizing what actually matters by risk, and tracking remediation through to closure.
• Researched emerging threats relevant to our environment, turning threat intelligence into clear, practical guidance on what to patch, watch, or harden next.
• Led the response to a security alert: triaging it, containing the issue, coordinating with the wider Cybersecurity team across time zones, and writing up the post-incident review so we are stronger next time.
• Kept the Manchester office running day to day as our sole on-site IT support: sorting hardware and software issues, managing accounts and access, setting up new starters, and being the friendly face people walk up to when something breaks.
• Taken your turn on the on-call rota, ready to respond when a critical issue or security incident does not keep office hours.

We’re looking for a cybersecurity professional with a minimum of 5 years of experience, ideally with a strong focus on vulnerability and threat research and management. Because you will be the security decision-maker on the ground in Manchester, often working independently of the wider US-based team, we need someone who has already built the judgement that only comes with time in the field: knowing which vulnerabilities to elevate, how to run an incident calmly under pressure, and when to ask for help.

Solid all‑round IT support skills across Windows environments, networking, and common business tools matter too, since you will be the one keeping the office running. Familiarity with vulnerability scanners, endpoint protection, and SIEM tooling is important, and an awareness of UK data protection requirements and frameworks such as Cyber Essentials or ISO 27001 is a welcome bonus. You should also be comfortable joining an on-call rota and collaborating across time zones.

• Humble, open, and curious
  . Security is a field where nobody knows everything and the threats keep changing. You ask questions, share what you learn, and treat being wrong as a chance to get better rather than something to hide.
• Calm and decisive under pressure
  . When an incident hits, people look to you. You can hold steady, work the problem methodically, and make sensible calls with imperfect information.
• Self‑directed and dependable
  . As the only IT and security person in the office, you take ownership without waiting to be told, manage your own priorities, and follow through so colleagues can trust that things are handled.
• A clear and approachable communicator
  . You can explain a security risk to a senior leader and patiently help a colleague with a frozen screen, adjusting how you talk to whoever is in front of you.

Given the sensitive nature of the work we do and the law enforcement agencies we serve, the successful candidate will be required…