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Fix XSS issue from incomplete tags with no attributes (#694) #695

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Merged
nicholasserra merged 1 commit into from
Mar 28, 2026
+7 −1
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Fix XSS issue from incomplete tags with no attributes (#694) #695

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1 change: 1 addition & 0 deletions CHANGES.md
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Expand Up @@ -4,6 +4,7 @@

- [pull #687] Fix AssertionError hashing HTML blocks spread over multiple lines (#686)
- [pull #692] Fix XSS from code spans in link titles (#691)
- [pull #695] Fix XSS issue from incomplete tags with no attributes (#694)


## python-markdown2 2.5.5
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2 changes: 1 addition & 1 deletion lib/markdown2.py
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Expand Up @@ -2215,7 +2215,7 @@ def _encode_amps_and_angles(self, text: str) -> str:
text = self._naked_gt_re.sub('>', text)
return text

_incomplete_tags_re = re.compile(r"\\*<(!--|/?\w+?(?!\w)\s*?.+?(?:[\s/]+?|$))")
_incomplete_tags_re = re.compile(r"\\*<(!--|/?\w+?(?!\w)\s*?.*?(?:[\s/]+?|$))")

def _encode_incomplete_tags(self, text: str) -> str:
if self.safe_mode not in ("replace", "escape"):
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2 changes: 2 additions & 0 deletions test/tm-cases/incomplete_tag_xss_issue694.html
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@@ -0,0 +1,2 @@
<p>&lt;iframe
&lt;http:&gt; srcdoc="&lt;script&gt;alert()&lt;/script&gt;" a=</p>
1 change: 1 addition & 0 deletions test/tm-cases/incomplete_tag_xss_issue694.opts
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@@ -0,0 +1 @@
{'safe_mode': 'escape'}
2 changes: 2 additions & 0 deletions test/tm-cases/incomplete_tag_xss_issue694.text
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@@ -0,0 +1,2 @@
<iframe
<http:> srcdoc="<script>alert()</script>" a=
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