Fuzz GET parameter on a target website and [f]ilter out message [s]ize response of 4242 bytes

ffuf

Subdomain and directory discovery tool.
More information: <https://github.com/ffuf/ffuf>.
Trick copyright: tl;dr; <https://github.com/tldr-pages/tldr>

ffuf -w {{path/to/param_names.txt}} -u {{https://target/script.php?FUZZ=test_value}} -fs {{4242}}

click the source code to copy