The vulnerability in livebook-dev livebook involves improper origin validation in the handling of keyboard events between a sandboxed iframe and the parent page. The trusted iframe forwards every keydown event it receives to the parent page without checking if the event is trusted, allowing untrusted JavaScript inside the iframe to synthesize keyboard events that trigger global shortcuts. These shortcuts include forced full evaluation of all notebook cells, runtime restart, and cell deletion. This means that opening a malicious notebook can cause arbitrary Elixir code execution on the user's runtime without explicit user action. The issue affects livebook versions from 0.5.0 before 0.18.7 and from 0.19.0 before 0.19.9.

An attacker can cause a user's livebook session to execute all notebook cells automatically, restart the runtime discarding in-memory state, or delete cells without user confirmation. This leads to forced execution of potentially malicious Elixir code, which can compromise the user's environment. Because outputs are mirrored to all connected clients, collaborators can also be affected when a malicious output is rendered. The vulnerability requires no privileges and can be triggered by simply opening a crafted notebook.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should avoid opening notebooks from untrusted sources. Monitor the livebook-dev project for updates addressing this origin validation error vulnerability.