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Electron: Registry key path injection in app.setAsDefaultProtocolClient on Windows

Moderate severity GitHub Reviewed Published Apr 2, 2026 in electron/electron • Updated Apr 6, 2026

Package

npm electron (npm)

Affected versions

< 38.8.6
>= 39.0.0-alpha.1, < 39.8.1
>= 40.0.0-alpha.1, < 40.8.1
>= 41.0.0-alpha.1, < 41.0.0

Patched versions

38.8.6
39.8.1
40.8.1
41.0.0

Description

Impact

On Windows, app.setAsDefaultProtocolClient(protocol) did not validate the protocol name before writing to the registry. Apps that pass untrusted input as the protocol name may allow an attacker to write to arbitrary subkeys under HKCU\Software\Classes\, potentially hijacking existing protocol handlers.

Apps are only affected if they call app.setAsDefaultProtocolClient() with a protocol name derived from external or untrusted input. Apps that use a hardcoded protocol name are not affected.

Workarounds

Validate the protocol name matches /^[a-zA-Z][a-zA-Z0-9+.-]*$/ before passing it to app.setAsDefaultProtocolClient().

Fixed Versions

  • 41.0.0
  • 40.8.1
  • 39.8.1
  • 38.8.6

For more information

If there are any questions or comments about this advisory, please email security@electronjs.org

References

@VerteDinde VerteDinde published to electron/electron Apr 2, 2026
Published to the GitHub Advisory Database Apr 3, 2026
Reviewed Apr 3, 2026
Published by the National Vulnerability Database Apr 4, 2026
Last updated Apr 6, 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
Local
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
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:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/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.
(8th percentile)

Weaknesses

Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Learn more on MITRE.

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Learn more on MITRE.

CVE ID

CVE-2026-34773

GHSA ID

GHSA-mwmh-mq4g-g6gr

Source code

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