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Fix XSS from code spans in image alt text (#699) #700

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Merged
nicholasserra merged 1 commit into from
Apr 30, 2026
+8 −0
Merged

Fix XSS from code spans in image alt text (#699) #700

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1 change: 1 addition & 0 deletions CHANGES.md
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Expand Up @@ -5,6 +5,7 @@
- [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)
- [pull #700] Fix XSS from code spans in image alt text (#699)


## python-markdown2 2.5.5
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4 changes: 4 additions & 0 deletions lib/markdown2.py
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Expand Up @@ -3279,6 +3279,10 @@ def run(self, text: str):
curr_pos = start_idx + 1
continue

if link_text and self.md.safe_mode:
# expose code span contents for escaping - fix #699
link_text = self.md._unhash_html_spans(link_text, spans=False, code=True)

start_idx -= 1
result, skip = self.process_image(url, title_str, link_text)
elif start_idx >= anchor_allowed_pos:
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1 change: 1 addition & 0 deletions test/tm-cases/xss_issue699.html
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@@ -0,0 +1 @@
<p><img src="" alt="&lt;code&gt;&quot; onerror=&quot;alert(1)//&lt;/code&gt;" /></p>
1 change: 1 addition & 0 deletions test/tm-cases/xss_issue699.opts
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@@ -0,0 +1 @@
{"safe_mode": "escape"}
1 change: 1 addition & 0 deletions test/tm-cases/xss_issue699.text
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@@ -0,0 +1 @@
![`" onerror="alert(1)//`]()
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