Electron: openExternal permission requests can be attributed to the wrong origin

Overview

Impact

Requests to open external protocol URLs could be attributed to a document other than the one that asked for them, so the requestingUrl passed to session.setPermissionRequestHandler was a trusted origin for a launch untrusted content had requested. An origin-based handler could therefore let untrusted content launch an OS-registered external application.

Apps are only affected if they grant openExternal based on the requesting origin and let untrusted content open or navigate windows. Apps whose permission handler denies openExternal for untrusted content are not affected.

Workarounds

Deny the openExternal permission for untrusted content, or deny the windows it opens with setWindowOpenHandler.

Fixed Versions

• 45.0.0-alpha.5
• 44.3.0
• 43.7.0
• 42.11.3

For more information

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

Affected packages

• electron < 42.11.3
• electron >= 43.0.0-alpha.1, < 43.7.0
• electron >= 44.0.0-alpha.1, < 44.3.0
• electron >= 45.0.0-alpha.1, < 45.0.0-alpha.5

Remediation

Upgrade to a patched release:

• electron 42.11.3
• electron 43.7.0
• electron 44.3.0
• electron 45.0.0-alpha.5