User input in format string detected.

• Rule ID: ruby_lang_format_string_using_user_input
• Languages: ruby
• Source: format_string_using_user_input.yml

Description

If an application includes user input directly in a format string, an attacker can use format specifiers in the user input to produce misleading or fabricated messages.

Remediations

❌ Avoid format strings containing user input:

sprintf("The value was #{params[:value]}")

✅ Use a literal format string with additional arguments:

sprintf("The value was %s", params[:value])

Associated CWE

• CWE-134: Use of Externally-Controlled Format String