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Electron: ProtocolResponse.url reuses the default session cache instead of the registering session

Moderate severity GitHub Reviewed Published Jul 27, 2026 in electron/electron • Updated Aug 5, 2026

Package

npm electron (npm)

Affected versions

>= 43.0.0-alpha.1, < 43.0.0
>= 42.0.0-alpha.1, < 42.5.1
>= 41.0.0-alpha.1, < 41.9.1
>= 40.0.0-alpha.1, < 40.10.6

Patched versions

43.0.0
42.5.1
41.9.1
40.10.6

Description

Impact

When a custom protocol handler returned a ProtocolResponse with a url and no session, Electron made the upstream request through defaultSession instead of the session that handled the protocol. A cached response could then be reused across otherwise isolated session partitions.

Apps that use ProtocolResponse.url, omit ProtocolResponse.session, and rely on separate sessions to isolate content are affected. Apps that set an explicit session, or that do not isolate content across sessions, are not affected.

Workarounds

Set ProtocolResponse.session explicitly so the request uses the intended session's cache.

Fixed Versions

  • 43.0.0
  • 42.5.1
  • 41.9.1
  • 40.10.6

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
Last updated 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
None
User interaction
Required
Scope
Unchanged
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:N/UI:R/S:U/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.
(5th percentile)

Weaknesses

Exposure of Resource to Wrong Sphere

The product exposes a resource to the wrong control sphere, providing unintended actors with inappropriate access to the resource. Learn more on MITRE.

CVE ID

CVE-2026-70606

GHSA ID

GHSA-r4w5-6pfg-jxp5

Source code

Credits

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