Analyzing bucket: {bucket_name}
\"\n return render_template_string(template_markup)","explanation":"User-controlled input from request parameters 'bucket' and 'title' are directly interpolated into an f-string to construct HTML markup, which is then passed to render_template_string(). This allows attackers to inject Jinja2 template expressions that will be evaluated server-side, leading to remote code execution.","remediation":"The fix replaces f-string interpolation of user input into the template string with Jinja2's native variable substitution using {{ }} placeholders. User-controlled values are passed as context variables to render_template_string(), which automatically escapes them, preventing any injected Jinja2 expressions from being interpreted as template code.","secure_code":"from flask import Flask, request, render_template_string\nimport boto3\nfrom markupsafe import escape\n\napp = Flask(__name__)\ns3_client = boto3.client('s3')\n\n@app.route('/cloud/bucket-report')\ndef generate_bucket_report():\n bucket_name = request.args.get('bucket', 'default-bucket')\n report_title = request.args.get('title', 'S3 Bucket Analysis')\n template_markup = \"Analyzing bucket: {{ bucket_name }}
\"\n return render_template_string(template_markup, report_title=report_title, bucket_name=bucket_name)"}