CERT-EU reports on ARTEX, backdoors in AI agent harnesses and CVE-2026-88771

CERT-EU reports that in recent weeks it observed several threat actors around the world using ARTEX, an AI-powered penetration-testing framework, to automate their campaigns. ARTEX rapidly identifies and exploits misconfigurations as well as traditional software vulnerabilities. CERT-EU also addresses possible backdoors in AI agent harnesses and an investigation that began with a rumour about a new, unpatched, pre-authentication remote code execution vulnerability affecting Citrix NetScaler.