Web Application Exploiting PostMessage Handlers to Achieve DOM XSS
A Synack Red Team member discovered a cross-site scripting vulnerability in SAP Concur Open.
Home > Archives by John Kounelis
John Kounelis
John Kounelis is a Senior Product Security Engineer with a strong foundation in software engineering and application security. With over five years of experience, he specializes in web application pentesting, source code review, and secure software development practices. John holds a Bachelor's degree in Computer Science, a Master of Science in Cybersecurity, and industry-recognized certifications including the OSWE and OSCP. He is an active member of the Synack Red Team and was inducted into the elite Synack Acropolis program in 2026. Known for his developer-first perspective on AppSec, John brings a unique and practical approach to finding and fixing real-world vulnerabilities.