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Add id attribute to DOM clobbering note #11754

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Add id attribute to DOM clobbering note #11754

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23 changes: 19 additions & 4 deletions source
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Expand Up @@ -59478,7 +59478,8 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s

<div class="note">
<p>DOM clobbering is a common cause of security issues. Avoid using the names of
built-in form properties with the <code data-x="attr-fe-name">name</code> content attribute.</p>
built-in form properties with the <code data-x="attr-fe-name">name</code> and <code
data-x="attr-id">id</code> content attributes.</p>

<p>In this example, the <code>input</code> element overrides the built-in <code
data-x="attr-fs-method">method</code> property:</p>
Expand All @@ -59491,9 +59492,23 @@ form.method; // => "get"
input.name = "method"; // DOM clobbering occurs here
form.method === input; // => true</code></pre>

<p>Since the input name takes precedence over built-in form properties, the JavaScript reference
<code data-x="">form.method</code> will point to the <code>input</code> element named "method"
instead of the built-in <code data-x="attr-fs-method">method</code> property.</p>
<p>The same issue occurs with the <code data-x="attr-id">id</code> attribute and the <code
data-x="attr-fs-enctype">enctype</code> property:</p>

<pre><code class="js">let form = document.createElement("form");
let input = document.createElement("input");
form.appendChild(input);

form.enctype; // => "application/x-www-form-urlencoded"
input.id = "enctype"; // DOM clobbering occurs here as well
form.enctype === input; // => true</code></pre>

<p>Since the input <code data-x="attr-fe-name">name</code> and <code data-x="attr-id">id</code>
take precedence over built-in form properties, the JavaScript references <code
data-x="">form.method</code> and <code data-x="">form.enctype</code> will point to the
corresponding <code>input</code> elements instead of the built-in <code
data-x="attr-fs-method">method</code> and <code data-x="attr-fs-enctype">enctype</code>
properties.</p>
</div>


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