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Electron: HTTP Response Header Injection in custom protocol handlers and webRequest

Moderate severity GitHub Reviewed Published Apr 2, 2026 in electron/electron • Updated Apr 3, 2026

Package

npm electron (npm)

Affected versions

< 38.8.6
>= 39.0.0-alpha.1, < 39.8.3
>= 40.0.0-alpha.1, < 40.8.3
>= 41.0.0-alpha.1, < 41.0.3

Patched versions

38.8.6
39.8.3
40.8.3
41.0.3

Description

Impact

Apps that register custom protocol handlers via protocol.handle() / protocol.registerSchemesAsPrivileged() or modify response headers via webRequest.onHeadersReceived may be vulnerable to HTTP response header injection if attacker-controlled input is reflected into a response header name or value.

An attacker who can influence a header value may be able to inject additional response headers, affecting cookies, content security policy, or cross-origin access controls.

Apps that do not reflect external input into response headers are not affected.

Workarounds

Validate or sanitize any untrusted input before including it in a response header name or value.

Fixed Versions

  • 41.0.3
  • 40.8.3
  • 39.8.3
  • 38.8.6

For more information

If there are any questions or comments about this advisory, send an email to 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
Last updated Apr 3, 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
Low
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:N/AC:H/PR:N/UI:R/S:U/C:L/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 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.

Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. Learn more on MITRE.

CVE ID

CVE-2026-34767

GHSA ID

GHSA-4p4r-m79c-wq3v

Source code

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