Fix Shadow API Exposure in Fresh
Shadow APIs in Fresh occur when undocumented endpoints are leaked via automatic file-system routing. In Deno's Fresh framework, every file in the routes/ directory is a public entry point. Attackers use specialized wordlists to discover these 'forgotten' handlers that lack middleware protection or proper visibility controls.
The Vulnerable Pattern
// routes/api/debug_internal_user_data.ts import { Handlers } from "$fresh/server.ts"; import { kv } from "../../utils/db.ts";
export const handler: Handlers = { async GET(_req, _ctx) { // VULNERABILITY: No authentication and route is discoverable via brute-force const users = await kv.list({ prefix: [“users”] }); const result = []; for await (const res of users) result.push(res.value); return new Response(JSON.stringify(result)); }, };
The Secure Implementation
To eliminate Shadow APIs in Fresh: 1. Implement directory-level middleware (_middleware.ts) to enforce 'Secure by Default' access patterns. 2. Use explicit environment variable checks for any administrative or internal-only routes. 3. Audit the routes/ directory for legacy scripts or 'debug' files that Deno automatically exposes. 4. Use Zod or similar schema validators to ensure that even if a route is discovered, it does not leak unexpected internal state via over-posting or mass assignment.
// routes/api/_middleware.ts import { MiddlewareHandlerContext } from "$fresh/server.ts";export async function handler(req: Request, ctx: MiddlewareHandlerContext) { const apiKey = req.headers.get(“X-Internal-Key”); if (apiKey !== Deno.env.get(“INTERNAL_API_SECRET”)) { return new Response(“Forbidden”, { status: 403 }); } return await ctx.next(); }
// routes/api/metrics.ts import { Handlers } from “$fresh/server.ts”;
export const handler: Handlers = { async GET(_req, _ctx) { // Handler is now protected by the directory-level middleware return new Response(JSON.stringify({ status: “ok” })); }, };
Your Fresh API
might be exposed to Shadow API Exposure
74% of Fresh apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
Free Tier • No Credit Card • Instant Report
Verified by Ghost Labs Security Team
This content is continuously validated by our automated security engine and reviewed by our research team. Ghost Labs analyzes over 500+ vulnerability patterns across 40+ frameworks to provide up-to-date remediation strategies.