Electron: Sandboxed iframes can launch external protocol handlers

### Impact Requests to open external protocol URLs from web content did not take iframe sandbox restrictions into account, so a sandboxed iframe could cause an OS-registered external application to be launched. The frame's sandbox state was also not made available to the app's permission handlers. Apps are only affected if they render untrusted content in sandboxed iframes and grant the `openExternal` permission (granted by default when no `setPermissionRequestHandler` is installed). Apps whose permission handler denies `openExternal` for untrusted content are not affected. ### Workarounds Install a `setPermissionRequestHandler` that denies the `openExternal` permission for untrusted content. ### Fixed Versions * `42.0.0-beta.3` * `41.2.1` * `40.9.0` * `39.8.8` ### For more information If you have any questions or comments about this advisory, email Electron at [[email protected]](mailto:[email protected])

Source published

5 Aug 2026 17:56:50 UTC

Source modified

5 Aug 2026 18:11:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

Publisher rating · MODERATE