https://github.com/python/cpython/commit/0cbbfc462119b9107b373c24d2bda5a1271bed36
commit: 0cbbfc462119b9107b373c24d2bda5a1271bed36
branch: main
author: Serhiy Storchaka <[email protected]>
committer: serhiy-storchaka <[email protected]>
date: 2025-08-14T18:13:22Z
summary:
gh-135661: Fix CDATA section parsing in HTMLParser (GH-135665)
"] ]>" and "]] >" no longer end the CDATA section.
Make CDATA section parsing context depending.
Add private method HTMLParser._set_support_cdata() to change the context.
If called with True, "<[CDATA[" starts a CDATA section which ends with "]]>".
If called with False, "<[CDATA[" starts a bogus comments which ends with ">".
files:
A Misc/NEWS.d/next/Security/2025-06-18-13-34-55.gh-issue-135661.NZlpWf.rst
M Lib/html/parser.py
M Lib/test/test_htmlparser.py
diff --git a/Lib/html/parser.py b/Lib/html/parser.py
index 5d03c98df5cdd0..75bf8adae6d70a 100644
--- a/Lib/html/parser.py
+++ b/Lib/html/parser.py
@@ -146,6 +146,7 @@ def reset(self):
self.lasttag = '???'
self.interesting = interesting_normal
self.cdata_elem = None
+ self._support_cdata = True
self._escapable = True
super().reset()
@@ -183,6 +184,19 @@ def clear_cdata_mode(self):
self.cdata_elem = None
self._escapable = True
+ def _set_support_cdata(self, flag=True):
+ """Enable or disable support of the CDATA sections.
+ If enabled, "<[CDATA[" starts a CDATA section which ends with "]]>".
+ If disabled, "<[CDATA[" starts a bogus comments which ends with ">".
+
+ This method is not called by default. Its purpose is to be called
+ in custom handle_starttag() and handle_endtag() methods, with
+ value that depends on the adjusted current node.
+ See
https://html.spec.whatwg.org/multipage/parsing.html#markup-declaration-open-state
+ for details.
+ """
+ self._support_cdata = flag
+
# Internal -- handle data as far as reasonable. May leave state
# and data to be processed by a subsequent call. If 'end' is
# true, force handling all data as if followed by EOF marker.
@@ -258,7 +272,10 @@ def goahead(self, end):
break
self.handle_comment(rawdata[i+4:j])
elif startswith("<![CDATA[", i):
- self.unknown_decl(rawdata[i+3:])
+ if self._support_cdata:
+ self.unknown_decl(rawdata[i+3:])
+ else:
+ self.handle_comment(rawdata[i+1:])
elif rawdata[i:i+9].lower() == '<!doctype':
self.handle_decl(rawdata[i+2:])
elif startswith("<!", i):
@@ -334,7 +351,14 @@ def parse_html_declaration(self, i):
# this case is actually already handled in goahead()
return self.parse_comment(i)
elif rawdata[i:i+9] == '<![CDATA[':
- return self.parse_marked_section(i)
+ if self._support_cdata:
+ j = rawdata.find(']]>', i+9)
+ if j < 0:
+ return -1
+ self.unknown_decl(rawdata[i+3: j])
+ return j + 3
+ else:
+ return self.parse_bogus_comment(i)
elif rawdata[i:i+9].lower() == '<!doctype':
# find the closing >
gtpos = rawdata.find('>', i+9)
diff --git a/Lib/test/test_htmlparser.py b/Lib/test/test_htmlparser.py
index 380bbe40177ec5..fff41dab321acd 100644
--- a/Lib/test/test_htmlparser.py
+++ b/Lib/test/test_htmlparser.py
@@ -10,10 +10,13 @@
class EventCollector(html.parser.HTMLParser):
- def __init__(self, *args, **kw):
+ def __init__(self, *args, autocdata=False, **kw):
+ self.autocdata = autocdata
self.events = []
self.append = self.events.append
html.parser.HTMLParser.__init__(self, *args, **kw)
+ if autocdata:
+ self._set_support_cdata(False)
def get_events(self):
# Normalize the list of events so that buffer artefacts don't
@@ -34,12 +37,16 @@ def get_events(self):
def handle_starttag(self, tag, attrs):
self.append(("starttag", tag, attrs))
+ if self.autocdata and tag == 'svg':
+ self._set_support_cdata(True)
def handle_startendtag(self, tag, attrs):
self.append(("startendtag", tag, attrs))
def handle_endtag(self, tag):
self.append(("endtag", tag))
+ if self.autocdata and tag == 'svg':
+ self._set_support_cdata(False)
# all other markup
@@ -767,10 +774,6 @@ def test_eof_in_declarations(self):
('<!', [('comment', '')]),
('<!-', [('comment', '-')]),
('<![', [('comment', '[')]),
- ('<![CDATA[', [('unknown decl', 'CDATA[')]),
- ('<![CDATA[x', [('unknown decl', 'CDATA[x')]),
- ('<![CDATA[x]', [('unknown decl', 'CDATA[x]')]),
- ('<![CDATA[x]]', [('unknown decl', 'CDATA[x]]')]),
('<!DOCTYPE', [('decl', 'DOCTYPE')]),
('<!DOCTYPE ', [('decl', 'DOCTYPE ')]),
('<!DOCTYPE html', [('decl', 'DOCTYPE html')]),
@@ -783,6 +786,18 @@ def test_eof_in_declarations(self):
for html, expected in data:
self._run_check(html, expected)
+ @support.subTests('content', ['', 'x', 'x]', 'x]]'])
+ def test_eof_in_cdata(self, content):
+ self._run_check('<![CDATA[' + content,
+ [('unknown decl', 'CDATA[' + content)])
+ self._run_check('<![CDATA[' + content,
+ [('comment', '![CDATA[' + content)],
+ collector=EventCollector(autocdata=True))
+ self._run_check('<svg><text y="100"><![CDATA[' + content,
+ [('starttag', 'svg', []),
+ ('starttag', 'text', [('y', '100')]),
+ ('unknown decl', 'CDATA[' + content)])
+
def test_bogus_comments(self):
html = ('<!ELEMENT br EMPTY>'
'<! not really a comment >'
@@ -845,28 +860,53 @@ def test_broken_condcoms(self):
]
self._run_check(html, expected)
- def test_cdata_declarations(self):
- # More tests should be added. See also "8.2.4.42. Markup
- # declaration open state", "8.2.4.69. CDATA section state",
- # and issue 32876
- html = ('<![CDATA[just some plain text]]>')
- expected = [('unknown decl', 'CDATA[just some plain text')]
+ @support.subTests('content', [
+ 'just some plain text',
+ '<!-- not a comment -->',
+ '¬-an-entity-ref;',
+ "<not a='start tag'>",
+ '',
+ '[[I have many brackets]]',
+ 'I have a > in the middle',
+ 'I have a ]] in the middle',
+ '] ]>',
+ ']] >',
+ ('\n'
+ ' if (a < b && a > b) {\n'
+ ' printf("[<marquee>How?</marquee>]");\n'
+ ' }\n'),
+ ])
+ def test_cdata_section_content(self, content):
+ # See "13.2.5.42 Markup declaration open state",
+ # "13.2.5.69 CDATA section state", and issue bpo-32876.
+ html = f'<svg><text y="100"><![CDATA[{content}]]></text></svg>'
+ expected = [
+ ('starttag', 'svg', []),
+ ('starttag', 'text', [('y', '100')]),
+ ('unknown decl', 'CDATA[' + content),
+ ('endtag', 'text'),
+ ('endtag', 'svg'),
+ ]
self._run_check(html, expected)
+ self._run_check(html, expected,
collector=EventCollector(autocdata=True))
- def test_cdata_declarations_multiline(self):
- html = ('<code><![CDATA['
- ' if (a < b && a > b) {'
- ' printf("[<marquee>How?</marquee>]");'
- ' }'
- ']]></code>')
+ def test_cdata_section(self):
+ # See "13.2.5.42 Markup declaration open state".
+ html = ('<![CDATA[foo<br>bar]]>'
+ '<svg><text y="100"><![CDATA[foo<br>bar]]></text></svg>'
+ '<![CDATA[foo<br>bar]]>')
expected = [
- ('starttag', 'code', []),
- ('unknown decl',
- 'CDATA[ if (a < b && a > b) { '
- 'printf("[<marquee>How?</marquee>]"); }'),
- ('endtag', 'code')
+ ('comment', '[CDATA[foo<br'),
+ ('data', 'bar]]>'),
+ ('starttag', 'svg', []),
+ ('starttag', 'text', [('y', '100')]),
+ ('unknown decl', 'CDATA[foo<br>bar'),
+ ('endtag', 'text'),
+ ('endtag', 'svg'),
+ ('comment', '[CDATA[foo<br'),
+ ('data', 'bar]]>'),
]
- self._run_check(html, expected)
+ self._run_check(html, expected,
collector=EventCollector(autocdata=True))
def test_convert_charrefs_dropped_text(self):
# #23144: make sure that all the events are triggered when
diff --git
a/Misc/NEWS.d/next/Security/2025-06-18-13-34-55.gh-issue-135661.NZlpWf.rst
b/Misc/NEWS.d/next/Security/2025-06-18-13-34-55.gh-issue-135661.NZlpWf.rst
new file mode 100644
index 00000000000000..fe000d936aae9d
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2025-06-18-13-34-55.gh-issue-135661.NZlpWf.rst
@@ -0,0 +1,5 @@
+Fix CDATA section parsing in :class:`html.parser.HTMLParser` according to
+the HTML5 standard: ``] ]>`` and ``]] >`` no longer end the CDATA section.
+Add private method ``_set_support_cdata()`` which can be used to specify
+how to parse ``<[CDATA[`` --- as a CDATA section in foreign content
+(SVG or MathML) or as a bogus comment in the HTML namespace.
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