Electron: Context isolation bypass via Function.prototype.bind hijack

Impact

Apps that expose Promise-returning functions to web content via contextBridge may be vulnerable to a context isolation bypass. Untrusted web content could obtain access to the isolated preload world and, through it, every capability the preload script has. In renderers without a sandbox, or with nodeIntegration enabled, this may escalate to Node.js access.

Apps are affected if they expose Promise-returning functions via contextBridge — the standard pattern for wrapping ipcRenderer.invoke — in windows that load untrusted content. Apps that never load untrusted content in those windows are not affected.

Workarounds

There are no app side workarounds, you must update to a patched version of Electron.

Fixed

Versions * 42.0.0-beta.5 * 41.2.2 * 40.9.2 * 39.8.9

For more information

If you have any questions or comments about this advisory, email Electron at [email protected]