Overview
Jeroen Gui is the founder of JustGuard, a company he started in August 2023, and is based in Leuven. His stated areas of expertise are cyber threat intelligence, cybersecurity, IT security operations, entrepreneurship and business development.
He worked at Easi in blue team research and development during two periods in 2025, in June and July and again in October and November. From August 2023 to January 2024 he was an ethical phisher at OutKept. Earlier, he held several roles at Wina Leuven between 2021 and 2023, working as a system administrator and web developer and serving on the first-year welcoming committee, which he led as team leader from July 2022. In 2020 he was an information technology sales consultant at Elektromic NV, and in October 2019 he represented Belgium as a Euroscola student representative at the European Parliament.
Gui followed the Latijn-wiskunde track at Sint Dimpna Geel College, then took a bachelor's degree in computer science at KU Leuven, where he is also enrolled in a master's in information management.
Career history
In the news
- The International Cybersecurity Summerschool 2026 was so amazing that I don’t even know where to start. I could have asked my favourite LLM to give you a summary of the interesting lectures about securing OT and AI, table top cyber crisis exercises and visits to both Europol and NATO Communications and Information Agency (NCIA), but who’s waiting for that? What made this week the most special was the human connection. 56 people from 18 countries, learning from professionals in the field, and from each other while working on our final
- I'm very happy to share that I graduated with distinction from the Faculty of Economics and Business, KU Leuven. My master's thesis got awarded the BDO Award for best master thesis in Information Management. This recognition would not have been possible without the guidance of my supervisor Wouter Verbeke, daily mentor Romain Bérard and everyone who took the time to challenge my thinking and provide valuable feedback and support throughout the process. I am excited to take the next step and start my career in cybersecurity at
- As a kid, hacking the government sounded like something out of a movie. This week I actually did it. The legal way, of course. I'm proud to share that I've been added to the Centre for Cybersecurity Belgium (CCB) Wall of Fame after discovering and responsibly disclosing a security vulnerability through their Coordinated Vulnerability Disclosure (CVD) program. Huge thanks to the CCB team for their quick, professional follow-up and for fostering a culture where security researchers are welcomed instead of feared. That matters more than
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