CVE-2026-70602: Electron Auth Bypass Vulnerability

CVE-2026-70602 Overview

CVE-2026-70602 affects Electron, the framework for building cross-platform desktop applications with JavaScript, HTML, and CSS. The vulnerability stems from improper access control [CWE-284] in Electron's extension tabs and scripting APIs. These APIs were not scoped to the extension's own session. A malicious or compromised Chrome extension loaded through session.loadExtension could navigate, script, and read from windows belonging to a different session. This defeats the session isolation model that Electron applications rely on to separate untrusted extension content from other browsing contexts. The issue is fixed in Electron 39.8.8, 40.9.0, 41.2.1, and 42.0.0-beta.3.

Critical Impact
A compromised extension in one Electron session can cross into other sessions to read data and execute scripts, breaking the isolation boundary applications depend on for extension sandboxing.

Affected Products

Electron versions prior to 39.8.8
Electron 40.x versions prior to 40.9.0
Electron 41.x versions prior to 41.2.1 and 42.0.0-beta.x prior to 42.0.0-beta.3

Discovery Timeline

2026-08-05 - CVE-2026-70602 published to NVD
2026-08-05 - Last updated in NVD database

Technical Details for CVE-2026-70602

Vulnerability Analysis

Electron supports Chrome extensions through the session.loadExtension API. Applications commonly rely on distinct Session objects to isolate extension code from other application content, treating each session as a security boundary.

The extension chrome.tabs and chrome.scripting APIs did not enforce that boundary. When an extension called these APIs, Electron did not restrict operations to tabs and windows belonging to the same session as the extension. An extension loaded in one session could therefore enumerate tabs, inject scripts, and read window contents in unrelated sessions.

The issue impacts only applications that both load Chrome extensions and rely on separate Session instances to isolate those extensions from other content. Applications that do not load extensions, or that load extensions into the same session as all other content, are not affected.

Root Cause

The extension tab and scripting APIs were implemented without session-scoping checks, an improper access control flaw [CWE-284]. The APIs iterated across all tabs known to the Electron process rather than only those associated with the extension's own Session.

Attack Vector

Exploitation requires an attacker to control or compromise a Chrome extension already loaded by the host application. From that position, the extension calls the tabs or scripting APIs to reach content in a sibling session. Reported metrics indicate high attack complexity and high privileges required, reflecting the prerequisite that a malicious extension is already installed and loaded.

No synthetic exploitation code is published for this issue. Refer to the GitHub Security Advisory GHSA-m55f-7gqj-fr98 for maintainer-provided technical detail.

Detection Methods for CVE-2026-70602

Indicators of Compromise

Extensions invoking chrome.tabs.query, chrome.tabs.executeScript, or chrome.scripting.executeScript against tab identifiers that do not belong to the extension's own session.
Unexpected script injection or DOM reads in windows that should be isolated from any loaded extension.
Electron applications running vulnerable versions (< 39.8.8, < 40.9.0, < 41.2.1, < 42.0.0-beta.3) while using session.loadExtension.

Detection Strategies

Inventory deployed Electron applications and compare bundled runtime versions against the fixed releases.
Audit application source for calls to session.loadExtension combined with multi-session designs, which are the required preconditions for exposure.
Review loaded extensions for use of tabs and scripting permissions and monitor their runtime behavior in test builds.

Monitoring Recommendations

Log extension API calls in staging environments and alert on cross-session tab access patterns.
Track child renderer process creation and script execution in Electron applications through endpoint telemetry.
Watch for unexpected outbound network activity from extension processes, which can indicate data exfiltration following a cross-session read.

How to Mitigate CVE-2026-70602

Immediate Actions Required

Upgrade Electron to 39.8.8, 40.9.0, 41.2.1, or 42.0.0-beta.3 or later.
Rebuild and redistribute all downstream applications that embed a vulnerable Electron runtime.
Review the trust posture of every Chrome extension loaded via session.loadExtension and remove any that are not strictly required.

Patch Information

The Electron maintainers fixed the flaw by scoping the extension tabs and scripting APIs to the extension's own Session. Fixed versions are 39.8.8, 40.9.0, 41.2.1, and 42.0.0-beta.3. See the Electron GitHub Security Advisory for release details.

Workarounds

Stop calling session.loadExtension until the runtime is upgraded if session isolation of extensions is a security requirement.
Load extensions only into sessions that contain no other sensitive content, so cross-session reach provides no additional value to an attacker.
Restrict which extensions can be installed to a maintained allowlist signed by the application vendor.

bash

# Verify the Electron runtime version bundled with your application
npx electron --version

# Update to a fixed release using npm
npm install --save-dev electron@^41.2.1