fix(console): prevent open redirect in /auth/authorize continue parameter

packages/console/app/src/routes/auth/authorize.ts

@@ -1,10 +1,35 @@
 import type { APIEvent } from "@solidjs/start/server"
 import { AuthClient } from "~/context/auth"
 
+// Only allow `continue` values that are safe relative sub-paths appended to
+// `/auth/callback`. This prevents open-redirect / path-traversal style abuse
+// where a caller supplies e.g. `//evil.com`, `/../../evil`, or a value
+// containing a scheme, so that the resulting callback URL remains under the
+// `/auth/callback` prefix on the same origin.
+function safeContinue(cont: string): string {
+  if (!cont) return ""
+  // Must start with '/' and must not be a protocol-relative URL ('//...').
+  if (!cont.startsWith("/") || cont.startsWith("//")) return ""
+  // Reject backslashes (some parsers treat them like '/') and control chars.
+  if (/[\\\x00-\x1f]/.test(cont)) return ""
+  // Reject any path traversal segments.
+  const pathPart = cont.split(/[?#]/, 1)[0]
+  if (pathPart.split("/").some((seg) => seg === "..")) return ""
+  return cont
+}
+
 export async function GET(input: APIEvent) {
   const url = new URL(input.request.url)
-  const cont = url.searchParams.get("continue") ?? ""
+  const cont = safeContinue(url.searchParams.get("continue") ?? "")
   const callbackUrl = new URL(`./callback${cont}`, input.request.url)
+  // Defence in depth: ensure the resolved callback URL is still under the
+  // expected `/auth/callback` path on the same origin as the incoming request.
+  if (
+    callbackUrl.origin !== url.origin ||
+    !callbackUrl.pathname.startsWith("/auth/callback")
+  ) {
+    return new Response("invalid continue parameter", { status: 400 })
+  }
   const result = await AuthClient.authorize(callbackUrl.toString(), "code")
   return Response.redirect(result.url, 302)
 }