Fix JWT Vulnerabilities (Weak Signing, None Algo) in Hug
JWT handling in Hug/Python apps is a common failure point. Attackers exploit 'alg: none' to bypass authentication entirely or brute-force weak secrets. If your decode logic doesn't explicitly lock down the algorithm and use high-entropy keys, you're pwned by design. This guide enforces cryptographic integrity.
The Vulnerable Pattern
import hug import jwt
@hug.get(‘/api/admin’) def admin_portal(token): # VULNERABLE: Explicitly allowing ‘none’ algorithm or missing algorithm validation # Also uses a weak, hardcoded secret susceptible to brute-forcing try: header_data = jwt.decode(token, ‘super-secret’, algorithms=[‘HS256’, ‘none’]) return {‘status’: ‘access granted’, ‘data’: header_data} except Exception: return {‘error’: ‘Unauthorized’}
The Secure Implementation
To remediate JWT vulnerabilities in Hug, you must eliminate the 'none' algorithm exploit by passing a strict whitelist to the `algorithms` parameter in `jwt.decode()`. This prevents attackers from stripping the signature. Secondly, use `os.environ` to pull a strong, 256-bit secret key rather than hardcoding it, preventing offline dictionary attacks. Finally, always include the 'exp' (expiration) claim and use the `require` option to ensure tokens cannot be replayed indefinitely if intercepted.
import hug import jwt import os from hug.exceptions import AuthenticationFailedSECURE: Use environment variables for high-entropy secrets
SECRET_KEY = os.environ.get(‘JWT_SECRET_KEY’)
SECURE: Define a strict whitelist of allowed algorithms
ALLOWED_ALGORITHMS = [‘HS256’]
@hug.get(‘/api/admin’) def admin_portal(token): try: # SECURE: Enforce algorithm check and signature verification payload = jwt.decode( token, SECRET_KEY, algorithms=ALLOWED_ALGORITHMS, options={‘verify_signature’: True, ‘require’: [‘exp’, ‘iat’]} ) return {‘status’: ‘authenticated’, ‘user’: payload[‘sub’]} except jwt.PyJWTError as e: # Fail closed on any decoding or validation error raise AuthenticationFailed(‘Invalid Token Signature or Algorithm’)
Your Hug API
might be exposed to JWT Vulnerabilities (Weak Signing, None Algo)
74% of Hug apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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