Side-Channel Leakage from the File-Notification System on Linux, Android, Windows, and macOS. Accepted at The ACM Conference on Computer and Communications Security (CCS), November 15-19, 2026 — The Hague, Netherlands File-notification systems tell applications when files change, e.g., opened, closed, written, deleted. With only read permission on a file or directory, an attacker can watch these notifications and reconstruct user behavior. We find generic issues similar on each of Linux, Android, Windows, and macOS.