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fix: escape fallback raw-content ancestor tags in processing instructions #38

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fix: escape fallback raw-content ancestor tags in processing instructions #38

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8 changes: 7 additions & 1 deletion lib/NodeUtils.js
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Original file line number Diff line number Diff line change
Expand Up @@ -309,7 +309,13 @@ function serializeOne(kid, parent) {
s += '<!--' + commentData + '-->';
break;
case 7: //PROCESSING_INSTRUCTION_NODE
const content = escapeProcessingInstructionContent(kid.data);
let content = escapeProcessingInstructionContent(kid.data);
if (content.includes('</')) {
const fallbackTags = fallbackRawContentTags(parent);
for (const fallbackTag of fallbackTags) {
content = escapeMatchingClosingTag(content, fallbackTag);
}
}
s += '<?' + kid.target + ' ' + content + '?>';
break;
case 10: //DOCUMENT_TYPE_NODE
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21 changes: 21 additions & 0 deletions test/xss.js
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Expand Up @@ -509,6 +509,27 @@ exports.badProcessingInstruction = function () {
return alertFired(html).should.eventually.be.false('alert fired for: ' + html);
};

exports.noscriptProcessingInstructionAncestorClosingTagEscaped = function () {
const document = domino.createDocument('');
const noscript = document.createElement('noscript');
const pi = document.createProcessingInstruction('x', '</noscript ');
noscript.appendChild(pi);
const img = document.createElement('img');
img.setAttribute('src', 'x');
img.setAttribute('onerror', 'alert(1)');
noscript.appendChild(img);
document.body.appendChild(noscript);

document.body
.serialize()
.should.equal(
'<noscript><?x &lt;/noscript ?><img src="x" onerror="alert(1)"></noscript>',
);

const html = document.serialize();
return alertFired(html).should.eventually.be.false('alert fired for: ' + html);
};

exports.verifyEscapeMatchingClosingTag = function () {
const cases = [
['', 'style', ''], // no artifacts while processing an empty string
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