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Fix CVE-2018-5773: #285 #303

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Merged
merged 1 commit into from
Sep 26, 2018
Merged

Fix CVE-2018-5773: #285 #303

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10 changes: 9 additions & 1 deletion lib/markdown2.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1203,7 +1203,7 @@ def _is_auto_link(s):
self.html_spans[key] = sanitized
tokens.append(key)
else:
tokens.append(token)
tokens.append(self._encode_incomplete_tags(token))
is_html_markup = not is_html_markup
return ''.join(tokens)

Expand Down Expand Up @@ -2140,6 +2140,14 @@ def _encode_amps_and_angles(self, text):
text = self._naked_gt_re.sub('>', text)
return text

_incomplete_tags_re = re.compile("<(/?\w+\s+)")

def _encode_incomplete_tags(self, text):
if self.safe_mode not in ("replace", "escape"):
return text

return self._incomplete_tags_re.sub("&lt;\\1", text)

def _encode_backslash_escapes(self, text):
for ch, escape in list(self._escape_table.items()):
text = text.replace("\\"+ch, escape)
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3 changes: 3 additions & 0 deletions test/tm-cases/CVE-2018-5773.html
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@@ -0,0 +1,3 @@
<p>&lt;img src="" onerror=alert(/XSS/) </p>

<p>&lt;/img src="" onerror=alert(/XSS/) </p>
1 change: 1 addition & 0 deletions test/tm-cases/CVE-2018-5773.opts
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@@ -0,0 +1 @@
{"safe_mode": "replace"}
3 changes: 3 additions & 0 deletions test/tm-cases/CVE-2018-5773.text
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
<img src="" onerror=alert(/XSS/)

</img src="" onerror=alert(/XSS/)
2 changes: 1 addition & 1 deletion test/tm-cases/basic_safe_mode.html
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Expand Up @@ -28,7 +28,7 @@

<p><img src="http://example.com&gt;[HTML_REMOVED]alert(1)[HTML_REMOVED]" alt="img3" /></p>

<p><img src="javascript:alert(1)"</p>
<p>&lt;img src="javascript:alert(1)"</p>

<p><img src="http://example.com/image.gif?h=200&amp;w=500" alt="ok img" /></p>

Expand Down