Fix Improper Assets Management in Nitro
Improper asset management in the Nitro engine (used by Nuxt) occurs when server-side routes expose internal directories or fail to sanitize file paths, leading to Local File Inclusion (LFI) or sensitive data leakage. Attackers exploit these endpoints to retrieve .env files, SSH keys, or source code by bypassing intended directory boundaries via path traversal.
The Vulnerable Pattern
// server/routes/assets/[...file].ts import { readFileSync } from 'node:fs'; import { resolve } from 'node:path';
export default defineEventHandler((event) => { const filename = event.context.params.file; // VULNERABLE: No validation on ‘filename’. // An attacker can pass ’../../.env’ to leak secrets. const path = resolve(‘assets’, filename); return readFileSync(path); });
The Secure Implementation
To fix improper asset management, you must implement strict path normalization and boundary validation. The secure implementation uses 'path.normalize' to resolve relative segments and then checks if the resulting absolute path starts with the designated 'ASSET_DIR'. This prevents directory traversal attacks. Additionally, instead of using 'readFileSync' which loads the entire file into memory, 'sendStream' is used to mitigate potential Denial of Service (DoS) attacks on large files. Always ensure your nitro.config.ts 'publicAssets' configuration excludes sensitive internal directories.
// server/routes/assets/[...file].ts import { createReadStream } from 'node:fs'; import { resolve, normalize, join } from 'node:path'; import { sendStream } from 'h3';const ASSET_DIR = resolve(‘assets’);
export default defineEventHandler((event) => { const filename = event.context.params.file;
// 1. Normalize path to resolve ’..’ and ’.’ segments const safePath = normalize(join(ASSET_DIR, filename));
// 2. Jailbreak Check: Ensure the resolved path is still within ASSET_DIR if (!safePath.startsWith(ASSET_DIR)) { throw createError({ statusCode: 403, statusMessage: ‘Access Denied’ }); }
// 3. Use streaming to prevent memory exhaustion (DoS) return sendStream(event, createReadStream(safePath)); });
Your Nitro API
might be exposed to Improper Assets Management
74% of Nitro apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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