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Electron: Extension tab APIs operate across session boundaries

Moderate severity GitHub Reviewed Published Jul 27, 2026 in electron/electron

Package

npm electron (npm)

Affected versions

< 39.8.8
>= 40.0.0-alpha.1, < 40.9.0
>= 41.0.0-alpha.1, < 41.2.1
>= 42.0.0-alpha.1, < 42.0.0-beta.3

Patched versions

39.8.8
40.9.0
41.2.1
42.0.0-beta.3

Description

Impact

Extension tab and scripting APIs were not scoped to the extension's own session. A malicious or compromised extension loaded into one session could navigate, script, and read from windows belonging to a different session.

Apps are only affected if they load Chrome extensions via session.loadExtension and rely on separate sessions to isolate that extension from other content. Apps that do not load extensions, or that use a single session, are not affected.

Workarounds

Only load extensions from sources you trust; do not rely on session separation alone to contain an extension.

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

References

@MarshallOfSound MarshallOfSound published to electron/electron Jul 27, 2026
Published to the GitHub Advisory Database Aug 5, 2026
Reviewed Aug 5, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(11th percentile)

Weaknesses

Improper Access Control

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Learn more on MITRE.

CVE ID

CVE-2026-70602

GHSA ID

GHSA-m55f-7gqj-fr98

Source code

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