fix(electron): validate external login URL scheme and callback port (#1621)

electron/external-login.cjs

@@ -0,0 +1,20 @@
+/**
+ * The login URL a server hands the desktop app goes to shell.openExternal,
+ * so only web pages pass: any other scheme (file:, smb:, ms-msdt:, ...)
+ * would launch whatever OS handler is registered for it.
+ */
+function isExternalLoginUrl(value) {
+  try {
+    const { protocol } = new URL(value);
+    return protocol === "https:" || protocol === "http:";
+  } catch {
+    return false;
+  }
+}
+
+/** A non-privileged port for the loopback callback listener. */
+function isCallbackPort(value) {
+  return Number.isInteger(value) && value >= 1024 && value <= 65535;
+}
+
+module.exports = { isExternalLoginUrl, isCallbackPort };

electron/main.cjs

@@ -36,6 +36,7 @@ const { quitApp } = require("./app-quit.cjs");
 const { selectLinuxPasswordStore } = require("./linux-password-store.cjs");
 const { resolveLocalShell, repairSpawnHelpers } = require("./local-shell.cjs");
 const { registerLocalFileHandlers } = require("./local-files.cjs");
+const { isExternalLoginUrl, isCallbackPort } = require("./external-login.cjs");
 
 const localTerminalSessions = new Map();
 
@@ -1663,6 +1664,12 @@ ipcMain.handle("get-embedded-server-status", () => {
 ipcMain.handle(
   "external-browser-login",
   async (_event, authUrl, callbackPort) => {
+    if (!isExternalLoginUrl(authUrl)) {
+      return { success: false, error: "Invalid authentication URL" };
+    }
+    if (!isCallbackPort(callbackPort)) {
+      return { success: false, error: "Invalid callback port" };
+    }
     const http = require("http");
 
     return new Promise((resolve) => {