CVE-2026-34767: Electron: HTTP Response Header Injection in custom protocol handlers and webRequest

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.