Benign agent skills can combine into attacks scanners miss
SkillCascade shows that individually harmless add-ons can combine into harmful behavior, so agent builders cannot treat clean skills as a safe system. One skill can weaken a medication-history signal, another downgrade the interaction, and a third hide the resulting alert. The paper releases a benchmark with 213 validated cascading cases and finds these attacks evade per-skill scanners and runtime monitors across representative agents and language models.