CVE-2026-70612: Electron: Sandboxed iframes can launch external protocol handlers

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-05 · updated 2026-10-08
Weakness: CWE-284

Description

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.

Affected products

electron: before 39.8.8; from 40.0.0 before 40.9.0; from 41.0.0 through 41.2.1; 42.0.0-alpha1, 42.0.0-alpha2, 42.0.0-alpha3, 42.0.0-alpha4, 42.0.0-alpha5, 42.0.0-alpha6 (+2) — fixed in 39.8.8, 40.9.0

How to fix

Upgrade to a fixed version: electron 39.8.8, 40.9.0. Check the vendor advisory for mitigations.

References

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