CVE-2026-70612: 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 security@electronjs.org
Other sources
Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. Prior to 39.8.8, 40.9.0, 41.2.1, and 42.0.0-beta.3, 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 sandbox state was also not made available to the app permission handlers, affecting apps that render untrusted content in sandboxed iframes and grant the openExternal permission by default when no setPermissionRequestHandler is installed. This issue is fixed in 39.8.8, 40.9.0, 41.2.1, and 42.0.0-beta.3.
— 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-beta.3 - Upgrade
Upgrade
npm/electronto a version that resolves this vulnerability.Fixed in 41.2.1 - Upgrade
Upgrade
npm/electronto a version that resolves this vulnerability.Fixed in 40.9.0 - Upgrade
Upgrade
npm/electronto a version that resolves this vulnerability.Fixed in 39.8.8 - Upgrade
Upgrade
Electronto a version that resolves this vulnerability.Fixed in 39.8.8 - Upgrade
Upgrade
Electronto a version that resolves this vulnerability.Fixed in 40.9.0 - Upgrade
Upgrade
Electronto a version that resolves this vulnerability.Fixed in 41.2.1 - Upgrade
Upgrade
Electronto a version that resolves this vulnerability.Fixed in 42.0.0-beta.3 - Configuration
Install a setPermissionRequestHandler that denies the openExternal permission for untrusted content.
Electron openExternal permission = deny for untrusted content
Event History
Frequently Asked Questions
What is the severity of CVE-2026-70612?
CVE-2026-70612 has a medium severity score of 5.4.
How do I fix CVE-2026-70612?
To mitigate CVE-2026-70612, update to the latest version of Electron that addresses the vulnerability.
What software is affected by CVE-2026-70612?
CVE-2026-70612 affects the Electron framework used in various npm applications.
What is the impact of CVE-2026-70612?
CVE-2026-70612 allows sandboxed iframes to launch OS-registered external applications unintentionally.
Is there a workaround for CVE-2026-70612?
Implementing strict validation of external protocol URLs and reviewing iframe sandbox policies may serve as a temporary workaround for CVE-2026-70612.