## Overview Versions of `validator` prior to 1.1.0 are affected by several cross-site scripting vulnerabilities due to bypasses discovered in the denylist-based filter. ## Proof of Concept Various inputs that could bypass the filter were discovered: Improper parsing of nested tags: ``` ~~<;s onmouseover="alert(1)">This is a test~~ ``` Incomplete filtering of javascript: URIs: ``` ">test ``` UI Redressing: ```

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``` Bypass via Nested Forbidden Strings: ``` prompt(1); ``` Additional bypasses were discovered by Krzysztof Kotowicz in 2012 when auditing CodeIgniter's XSS filtering function, which this code was based off of. ## Recommendation If you are a developer currently using the xss filter function from the validator package, you should consider replacing it with the escape filter function from the same package. This function replaces all instances of angle brackets (<, >), ampersands, and quotation marks, so no HTML tags will be processed. ## References - [XSS Filter Bypass in validator Node.js Module](https://nealpoole.com/blog/2013/07/xss-filter-bypass-in-validator-nodejs-module/) - [CodeIgniter <= 2.1.1 xss_clean() Cross Site Scripting filter bypass](http://blog.kotowicz.net/2012/07/codeigniter-210-xssclean-cross-site.html) - [GitHub Advisory](https://github.com/advisories/GHSA-q4qq-fm7q-cwp5)