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escaped HTML entities like > were unescaped in the final mjml output #54

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Feb 22, 2024
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escaped HTML entities like > were unescaped in the final mjml output #54

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6 changes: 6 additions & 0 deletions CHANGELOG.md
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@@ -1,4 +1,10 @@

0.11.0 (2024-02-xx)
-------------------

- security fix: escaped HTML entities like `>` were unescaped in the final mjml output, leading to potential injection of untrusted user data (reported by @sh-at-cs)


0.10.0 (2023-11-17)
------------------

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9 changes: 7 additions & 2 deletions mjml/elements/head/mj_style.py
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Expand Up @@ -10,10 +10,15 @@ class MjStyle(HeadComponent):
@classmethod
def default_attrs(cls):
return {
'inline' : '',
'inline': '',
}

def handler(self):
add = self.context['add']
inline_attr = 'inlineStyle' if (self.get_attr('inline') == 'inline') else 'style'
add(inline_attr, self.getContent())
html_str = self.getContent()
# CSS can contain child selectors (e.g. "h1 > p") beautifulsoup only
# returns escaped entities. To make these selectors work, we need to
# unescape these.
css_str = html_str.replace('>', '>')
add(inline_attr, css_str)
4 changes: 2 additions & 2 deletions mjml/mjml2html.py
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Expand Up @@ -116,7 +116,7 @@ def parse(_mjml, parentMjClass='', *, template_dir):
classes = ignore_empty(attributes.get('mj-class', '').split(' '))

# upstream parses text contents (+ comments) in mjml-parser-xml/index.js
content = _mjml.decode_contents(formatter=None)
content = _mjml.decode_contents()

attributesClasses = {}
for css_class in classes:
Expand Down Expand Up @@ -213,7 +213,7 @@ def _head_data_add(attr, *params):
for element in contentSoup.select(selector):
element[attrName] = value or ''

content = contentSoup.decode_contents(formatter=None)
content = contentSoup.decode_contents()

content = skeleton(
content=content,
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120 changes: 120 additions & 0 deletions tests/testdata/mj-text-escaped-html-expected.html
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@@ -0,0 +1,120 @@
<!doctype html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office">

<head>
<title>
</title>
<!--[if !mso]><!-->
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<!--<![endif]-->
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style type="text/css">
#outlook a {
padding: 0;
}

body {
margin: 0;
padding: 0;
-webkit-text-size-adjust: 100%;
-ms-text-size-adjust: 100%;
}

table,
td {
border-collapse: collapse;
mso-table-lspace: 0pt;
mso-table-rspace: 0pt;
}

img {
border: 0;
height: auto;
line-height: 100%;
outline: none;
text-decoration: none;
-ms-interpolation-mode: bicubic;
}

p {
display: block;
margin: 13px 0;
}

</style>
<!--[if mso]>
<noscript>
<xml>
<o:OfficeDocumentSettings>
<o:AllowPNG/>
<o:PixelsPerInch>96</o:PixelsPerInch>
</o:OfficeDocumentSettings>
</xml>
</noscript>
<![endif]-->
<!--[if lte mso 11]>
<style type="text/css">
.mj-outlook-group-fix { width:100% !important; }
</style>
<![endif]-->
<!--[if !mso]><!-->
<link href="https://fonts.googleapis.com/css?family=Ubuntu:300,400,500,700" rel="stylesheet" type="text/css">
<style type="text/css">
@import url(https://fonts.googleapis.com/css?family=Ubuntu:300,400,500,700);

</style>
<!--<![endif]-->
<style type="text/css">
@media only screen and (min-width:480px) {
.mj-column-per-100 {
width: 100% !important;
max-width: 100%;
}
}

</style>
<style media="screen and (min-width:480px)">
.moz-text-html .mj-column-per-100 {
width: 100% !important;
max-width: 100%;
}

</style>
<style type="text/css">
</style>
<style type="text/css">
</style>
</head>

<body style="word-spacing:normal;">
<div style="">
<!--[if mso | IE]><table align="center" border="0" cellpadding="0" cellspacing="0" class="" role="presentation" style="width:600px;" width="600" ><tr><td style="line-height:0px;font-size:0px;mso-line-height-rule:exactly;"><![endif]-->
<div style="margin:0px auto;max-width:600px;">
<table align="center" border="0" cellpadding="0" cellspacing="0" role="presentation" style="width:100%;">
<tbody>
<tr>
<td style="direction:ltr;font-size:0px;padding:20px 0;text-align:center;">
<!--[if mso | IE]><table role="presentation" border="0" cellpadding="0" cellspacing="0"><tr><td class="" style="vertical-align:top;width:600px;" ><![endif]-->
<div class="mj-column-per-100 mj-outlook-group-fix" style="font-size:0px;text-align:left;direction:ltr;display:inline-block;vertical-align:top;width:100%;">
<table border="0" cellpadding="0" cellspacing="0" role="presentation" style="vertical-align:top;" width="100%">
<tbody>
<tr>
<td align="left" style="font-size:0px;padding:10px 25px;word-break:break-word;">
<div style="font-family:Ubuntu, Helvetica, Arial, sans-serif;font-size:13px;line-height:1;text-align:left;color:#000000;">Pretty unsafe: &lt;script&gt;</div>
</td>
</tr>
</tbody>
</table>
</div>
<!--[if mso | IE]></td></tr></table><![endif]-->
</td>
</tr>
</tbody>
</table>
</div>
<!--[if mso | IE]></td></tr></table><![endif]-->
</div>
</body>

</html>
11 changes: 11 additions & 0 deletions tests/testdata/mj-text-escaped-html.mjml
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@@ -0,0 +1,11 @@
<mjml>
<mj-body>
<mj-section>
<mj-column>
<mj-text>
Pretty unsafe: &lt;script&gt;
</mj-text>
</mj-column>
</mj-section>
</mj-body>
</mjml>
1 change: 1 addition & 0 deletions tests/upstream_alignment_test.py
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Expand Up @@ -48,6 +48,7 @@
'mj-raw-head-with-tags',
'mj-social',
'mj-spacer',
'mj-text-escaped-html', # this test is security-critical
'mj-wrapper',
)

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