CVE-2026-34765: Electron named window.open targets not scoped to the opener's browsing context
Impact When a renderer calls window.open() with a target name, Electron did not correctly scope the named-window lookup to the opener's browsing context group. A renderer could navigate an existing child window that was opened by a different, unrelated renderer if both used the same target name. If that existing child was created with more permissive webPreferences (via setWindowOpenHandler's overrideBrowserWindowOptions), content loaded by the second renderer inherits those permissions.
Apps are only affected if they open multiple top-level windows with differing trust levels and use setWindowOpenHandler to grant child windows elevated webPreferences such as a privileged preload script. Apps that do not elevate child window privileges, or that use a single top-level window, are not affected.
Apps that additionally grant nodeIntegration: true or sandbox: false to child windows (contrary to the security recommendations) may be exposed to arbitrary code execution.
Workarounds Deny window.open() in renderers that load untrusted content by returning { action: 'deny' } from setWindowOpenHandler. Avoid granting child windows more permissive webPreferences than their opener.
Fixed Versions 42.0.0-alpha.5 41.1.0 40.8.5 39.8.5
For more information If you have any questions or comments about this advisory, email us at security@electronjs.org
Other sources
Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to 39.8.5, 40.8.5, 41.1.0, and 42.0.0-alpha.5, when a renderer calls window.open() with a target name, Electron did not correctly scope the named-window lookup to the opener's browsing context group. A renderer could navigate an existing child window that was opened by a different, unrelated renderer if both used the same target name. If that existing child was created with more permissive webPreferences (via setWindowOpenHandler's overrideBrowserWindowOptions), content loaded by the second renderer inherits those permissions. Apps are only affected if they open multiple top-level windows with differing trust levels and use setWindowOpenHandler to grant child windows elevated webPreferences such as a privileged preload script. Apps that do not elevate child window privileges, or that use a single top-level window, are not affected. Apps that additionally grant nodeIntegration: true or sandbox: false to child windows (contrary to the security recommendations) may be exposed to arbitrary code execution. This vulnerability is fixed in 39.8.5, 40.8.5, 41.1.0, and 42.0.0-alpha.5.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/electronto a version that resolves this vulnerability.Fixed in 42.0.0-alpha.5 - Upgrade
Upgrade
npm/electronto a version that resolves this vulnerability.Fixed in 41.1.0 - Upgrade
Upgrade
npm/electronto a version that resolves this vulnerability.Fixed in 40.8.5 - Upgrade
Upgrade
npm/electronto a version that resolves this vulnerability.Fixed in 39.8.5 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 39.8.5 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 40.8.5 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 41.1.0 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 42.0.0-alpha.5 - Configuration
In renderers that load untrusted content, deny window.open() by returning { action: 'deny' } from setWindowOpenHandler.
Electron renderer setWindowOpenHandler (window.open policy) = { action: 'deny' } - Configuration
Do not grant child windows more permissive webPreferences than their opener when using setWindowOpenHandler/overrideBrowserWindowOptions.
Electron (window.open child windows) webPreferences passed via setWindowOpenHandler overrideBrowserWindowOptions = Avoid granting more permissive webPreferences than the opener - Compensating control
Avoid granting child windows more permissive webPreferences such as nodeIntegration: true or sandbox: false; adhere to Electron security recommendations to reduce risk of arbitrary code execution.