XSS vulnerability locator
<p>I was reading an article about XSS filter evasion at <a href="https://www.owasp.org" rel="nofollow noreferrer">https://www.owasp.org</a>. One of the ways described in the article to locate a vulnerability was to try injecting the following:</p>

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<pre class="snippet-code-html lang-html prettyprint-override"><code>'';!--"&lt;XSS&gt;=&amp;{()}</code></pre>
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<p>Then, if there is a  tag in the document source, opposed to &lt;XSS&gt;, the site is vulnerable to XSS. Why does the snippet above bypass some XSS and escaping filters?</p>