CVE-2026-66298 JS-view sandboxed output can synthesize keyboard events to trigger unconfirmed global shortcuts
Untrusted JavaScript in Livebook notebooks can synthesize keyboard events to force code execution or restart runtimes without user confirmation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-66298?
CVE-2026-66298 is a high-severity vulnerability in livebook-dev livebook, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Origin Validation Error vulnerability in livebook-dev livebook allows untrusted notebook output JavaScript to trigger session-wide keyboard shortcuts, including forced evaluation of all cells and runtime restart.
Livebook's JS-view feature renders notebook-defined JavaScript inside a sandboxed, cross-origin iframe specifically because that JavaScript is untrusted. The trusted iframe shell in iframe/priv/static/iframe/v5.html forwards every keydown event fired in its own window to the parent page without consulting Event.isTrusted, so an event synthesized by the untrusted script through window.dispatchEvent is forwarded exactly as a genuine keystroke would be. The parent-side relay in assets/js/hooks/js_view.js reconstructs and re-dispatches it on the live page with no further validation, and because assets/js/hooks/session.js registers the global shortcut handler on the document in the capture phase, that handler acts on the replicated event regardless of how it was produced.
Sandboxed output JavaScript can therefore drive Livebook's session-wide keyboard shortcuts. Two of them reach LivebookWeb.SessionLive and execute immediately with no confirmation: the shortcut for queueing full evaluation runs every cell in the notebook, and the shortcut for reconnecting the runtime disconnects and reconnects it, discarding in-memory state. A third shortcut deletes the focused cell behind a confirmation dialog that the user can permanently dismiss, after which it too executes silently.
Forced full evaluation is the significant consequence, because it causes the notebook's own Elixir code to run without the user choosing to evaluate anything. A user who merely opens a notebook obtained from a third party, or reached from published documentation, can have its code executed on their runtime. Livebook also mirrors cell outputs to every connected client, so a malicious output triggers in a collaborator's browser as soon as it renders.
This issue affects livebook: from 0.5.0 before 0.18.7 and from 0.19.0 before 0.19.9.
Weakness: CWE-346
Which versions are affected by CVE-2026-66298?
1 open source package ship an affected version, including livebook. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
livebook Hex | From 0.5.0 | 0.18.7, 0.19.9 |
Products include Livebook Livebook.
How do I fix CVE-2026-66298?
Upgrade livebook to a fixed version for your release line: 0.18.7 or 0.19.9.
Is CVE-2026-66298 being exploited?
There is no known exploitation of CVE-2026-66298 in the wild and no public exploit code.
Other vulnerabilities in livebook-dev livebook
- CVE-2023-35174 Livebook Desktop's protocol handler can be exploited to execute arbitrary command on Windows
- CVE-2026-68746 Livebook Teams identity check fails open when the deployment group is unresolvable, allowing unauthenticated access
- CVE-2026-66881 Path traversal in imported file_entries name allows arbitrary file write via URL-type entry download
- CVE-2026-66885 Livebook Teams identity callback lacks state binding, allowing login CSRF
- CVE-2026-66297 Unescaped deployment environment variables in generated setup commands
Sources
Also known as EEF-CVE-2026-66298, GHSA-68c2-prqg-x62g.