Possible cross site scripting threat detected.

• Rule ID: java_lang_xss_response_writer
• Languages: java
• Source: xss_response_writer.yml

Description

Make sure to encode and sanitize any user input before passing it down to response.getWriter() to avoid cross-site scripting (XSS) attacks.

✅ Use an encoder to minimize XSS risk

  String userInput = req.getQueryString("user");
  String encodedUserInput = Encode.forHtml(userInput)
  response.getWriter().write(encodedUserInput)

✅ Even better, sanitize user input

  String userInput = req.getQueryString("user");
  String sanitizedUserInput = sanitize(userInput);
  response.getWriter().write(sanitizedUserInput);

Resources

• OWASP XSS Prevention Cheatsheet
• OWASP Java Encoder

Associated CWE

• CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

OWASP Top 10

• A03:2021 - Injection

Configuration

To skip this rule during a scan, use the following flag

bearer scan /path/to/your-project/ --skip-rule=java_lang_xss_response_writer

To run only this rule during a scan, use the following flag

bearer scan /path/to/your-project/ --only-rule=java_lang_xss_response_writer