Sysadmin + security researcher based in the Netherlands. Day job in healthcare IT — identity, auth, endpoint, the usual mess.

Focus

  • Identity & auth (Keycloak, Entra, OIDC/SAML flows)
  • Healthcare IT security (NEN 7510, AVG/GDPR, vendor risk)
  • Responsible disclosure

Disclosures

  • Keycloak policy-enforcer — authorization bypass (CVE-2026-9800, GHSA-f5p5-6xmx-p252) — authenticated authz bypass via substring URI match, CVSS 8.1, fixed in 26.6.4 / 26.0.10. Writeup.
  • libvncclient — Tight decoder heap overflow (CVE-2026-50538, GHSA-v9pm-47h4-jcq8) — pre-auth OOB write, CVSS 8.8, fixed in 6724d69. Writeup.

More pending coordinated disclosure.

Contact