Fix Unrestricted Resource Consumption in Flask
Resource exhaustion is a low-effort, high-impact DoS vector. In Flask, failing to bound incoming data or execution time allows an attacker to choke the event loop, saturate memory, or fill the disk. Stop trusting default configurations; they are often too permissive for production environments.
The Vulnerable Pattern
from flask import Flask, request
app = Flask(name)
@app.route(‘/process-data’, methods=[‘POST’])
def process_data():
# VULNERABILITY: No limit on request size
# An attacker can send a multi-gigabyte payload to crash the process
data = request.get_json()
# VULNERABILITY: Unbounded loop based on user input
# An attacker can provide a huge 'count' to spike CPU
iterations = request.args.get('count', type=int)
results = [i * 2 for i in range(iterations)]
return {"status": "done"}</code></pre>
The Secure Implementation
To mitigate Unrestricted Resource Consumption, you must implement three layers of defense. First, set 'MAX_CONTENT_LENGTH' in the Flask config to prevent memory exhaustion from massive HTTP bodies. Second, use 'Flask-Limiter' to throttle requests per IP, stopping attackers from flooding expensive endpoints. Third, always validate and hard-cap user-supplied integers that control loops or memory allocation. Without these, your app is a sitting duck for trivial Denial of Service attacks.
from flask import Flask, request, abort
from flask_limiter import Limiter
from flask_limiter.util import get_remote_address
app = Flask(name)
FIX 1: Enforce hard limit on request size (e.g., 1MB)
app.config[‘MAX_CONTENT_LENGTH’] = 1 * 1024 * 1024
FIX 2: Implement Rate Limiting to prevent brute-force consumption
limiter = Limiter(get_remote_address, app=app, default_limits=[“100 per hour”])
@app.route(‘/process-data’, methods=[‘POST’])
@limiter.limit(“5 per minute”)
def process_data():
# FIX 3: Validate and bound user input
iterations = request.args.get(‘count’, type=int)
if not iterations or iterations > 1000:
abort(400, description=“Count exceeds safety threshold”)
data = request.get_json()
results = [i * 2 for i in range(iterations)]
return {"status": "done"}</code></pre>
Your Flask API
might be exposed to Unrestricted Resource Consumption
74% of Flask 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.