diff --git a/django/utils/html.py b/django/utils/html.py
index a2686d065b..ac444cf8ee 100644
--- a/django/utils/html.py
+++ b/django/utils/html.py
@@ -425,14 +425,17 @@ class Urlizer:
potential_entity = middle[amp:]
escaped = html.unescape(potential_entity)
if escaped == potential_entity or escaped.endswith(";"):
- rstripped = middle.rstrip(";")
- amount_stripped = len(middle) - len(rstripped)
- if amp > -1 and amount_stripped > 1:
- # Leave a trailing semicolon as might be an entity.
- trail = middle[len(rstripped) + 1 :] + trail
- middle = rstripped + ";"
+ rstripped = middle.rstrip(self.trailing_punctuation_chars)
+ trail_start = len(rstripped)
+ amount_trailing_semicolons = len(middle) - len(middle.rstrip(";"))
+ if amp > -1 and amount_trailing_semicolons > 1:
+ # Leave up to most recent semicolon as might be an entity.
+ recent_semicolon = middle[trail_start:].index(";")
+ middle_semicolon_index = recent_semicolon + trail_start + 1
+ trail = middle[middle_semicolon_index:] + trail
+ middle = rstripped + middle[trail_start:middle_semicolon_index]
else:
- trail = middle[len(rstripped) :] + trail
+ trail = middle[trail_start:] + trail
middle = rstripped
trimmed_something = True
diff --git a/docs/ref/templates/builtins.txt b/docs/ref/templates/builtins.txt
index 25c8a83e60..ef5633a48b 100644
--- a/docs/ref/templates/builtins.txt
+++ b/docs/ref/templates/builtins.txt
@@ -2855,6 +2855,17 @@ Django's built-in :tfilter:`escape` filter. The default value for
email addresses that contain single quotes (``'``), things won't work as
expected. Apply this filter only to plain text.
+.. warning::
+
+ Using ``urlize`` or ``urlizetrunc`` can incur a performance penalty, which
+ can become severe when applied to user controlled values such as content
+ stored in a :class:`~django.db.models.TextField`. You can use
+ :tfilter:`truncatechars` to add a limit to such inputs:
+
+ .. code-block:: html+django
+
+ {{ value|truncatechars:500|urlize }}
+
.. templatefilter:: urlizetrunc
``urlizetrunc``
diff --git a/docs/releases/4.2.16.txt b/docs/releases/4.2.16.txt
index 9853004386..2a84186867 100644
--- a/docs/releases/4.2.16.txt
+++ b/docs/releases/4.2.16.txt
@@ -7,4 +7,9 @@ Django 4.2.16 release notes
Django 4.2.16 fixes one security issue with severity "moderate" and one
security issue with severity "low" in 4.2.15.
-...
+CVE-2024-45230: Potential denial-of-service vulnerability in ``django.utils.html.urlize()``
+===========================================================================================
+
+:tfilter:`urlize` and :tfilter:`urlizetrunc` were subject to a potential
+denial-of-service attack via very large inputs with a specific sequence of
+characters.
diff --git a/docs/releases/5.0.9.txt b/docs/releases/5.0.9.txt
index eb3dbe832d..50e94ea3f2 100644
--- a/docs/releases/5.0.9.txt
+++ b/docs/releases/5.0.9.txt
@@ -7,4 +7,9 @@ Django 5.0.9 release notes
Django 5.0.9 fixes one security issue with severity "moderate" and one security
issue with severity "low" in 5.0.8.
-...
+CVE-2024-45230: Potential denial-of-service vulnerability in ``django.utils.html.urlize()``
+===========================================================================================
+
+:tfilter:`urlize` and :tfilter:`urlizetrunc` were subject to a potential
+denial-of-service attack via very large inputs with a specific sequence of
+characters.
diff --git a/tests/template_tests/filter_tests/test_urlize.py b/tests/template_tests/filter_tests/test_urlize.py
index 8f84e62c92..546bd6c7d6 100644
--- a/tests/template_tests/filter_tests/test_urlize.py
+++ b/tests/template_tests/filter_tests/test_urlize.py
@@ -305,6 +305,28 @@ class FunctionTests(SimpleTestCase):
"http://testing.com/example.,:;)"!",
)
+ def test_trailing_semicolon(self):
+ self.assertEqual(
+ urlize("http://example.com?x=&", autoescape=False),
+ ''
+ "http://example.com?x=&",
+ )
+ self.assertEqual(
+ urlize("http://example.com?x=&;", autoescape=False),
+ ''
+ "http://example.com?x=&;",
+ )
+ self.assertEqual(
+ urlize("http://example.com?x=&;;", autoescape=False),
+ ''
+ "http://example.com?x=&;;",
+ )
+ self.assertEqual(
+ urlize("http://example.com?x=&.;...;", autoescape=False),
+ ''
+ "http://example.com?x=&.;...;",
+ )
+
def test_brackets(self):
"""
#19070 - Check urlize handles brackets properly
diff --git a/tests/utils_tests/test_html.py b/tests/utils_tests/test_html.py
index 82dbd58f12..035585ec10 100644
--- a/tests/utils_tests/test_html.py
+++ b/tests/utils_tests/test_html.py
@@ -374,6 +374,7 @@ class TestUtilsHtml(SimpleTestCase):
"&:" + ";" * 100_000,
"&.;" * 100_000,
".;" * 100_000,
+ "&" + ";:" * 100_000,
)
for value in tests:
with self.subTest(value=value):