WordPress / WordPress/WordPress-Coding-Standards

filter_input() doesn't mean variable is sanitized

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#512 3 comments 0 reactions 0 assignees View on GitHub

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Focus: Security Type: Enhancement Upstream: PHPCSExtra
Dominant language
PHP
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Description

filter_input() is listed as an escaping function. However if the third parameter isn't set, then no sanitization takes place.

Example:
URL: http://test.dev/?test=%3Cscript%3Ealert%281%29%3B%3C%2Fscript%3E

echo filter_input( INPUT_GET, 'test' );

vs.

echo filter_input( INPUT_GET, 'test', FILTER_SANITIZE_STRING );

Should detection of filter_input require manual inspection or is it possible to check if the third parameter is set?

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Research direction

Start by locating the rule that treats filter_input() as an escaping function and inspect how its arguments are analyzed. Compare calls with and without the third parameter, then check the rule's existing tests if available. Done means detection distinguishes unsanitized calls from calls that explicitly provide a sanitizing filter.

Written by the indexing model from the issue text.

Assessment

Tech stack
php
Domain
tooling
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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