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From 790eb058b0716c536a2f2e8d1c6d5079d776c22b Mon Sep 17 00:00:00 2001
From: Sarah Boyce <42296566+sarahboyce@users.noreply.github.com>
Date: Wed, 13 Nov 2024 15:06:23 +0100
Subject: [PATCH] [4.2.x] Fixed CVE-2024-53907 -- Mitigated potential DoS in
strip_tags().
Thanks to jiangniao for the report, and Shai Berger and Natalia Bidart
for the reviews.
CVE: CVE-2024-53907
Upstream-Status: Backport [https://github.com/django/django/commit/790eb058b0716c536a2f2e8d1c6d5079d776c22b]
Signed-off-by: Soumya Sambu <soumya.sambu@windriver.com>
---
django/utils/html.py | 10 ++++++++--
tests/utils_tests/test_html.py | 7 +++++++
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/django/utils/html.py b/django/utils/html.py
index 3cf1bfc..0d5ffd2 100644
--- a/django/utils/html.py
+++ b/django/utils/html.py
@@ -8,12 +8,14 @@ from urllib.parse import (
parse_qsl, quote, unquote, urlencode, urlsplit, urlunsplit,
)
+from django.core.exceptions import SuspiciousOperation
from django.utils.functional import Promise, keep_lazy, keep_lazy_text
from django.utils.http import RFC3986_GENDELIMS, RFC3986_SUBDELIMS
from django.utils.safestring import SafeData, SafeText, mark_safe
from django.utils.text import normalize_newlines
MAX_URL_LENGTH = 2048
+MAX_STRIP_TAGS_DEPTH = 50
# Configuration for urlize() function.
TRAILING_PUNCTUATION_CHARS = '.,:;!'
@@ -185,15 +187,19 @@ def _strip_once(value):
@keep_lazy_text
def strip_tags(value):
"""Return the given HTML with all tags stripped."""
- # Note: in typical case this loop executes _strip_once once. Loop condition
- # is redundant, but helps to reduce number of executions of _strip_once.
value = str(value)
+ # Note: in typical case this loop executes _strip_once twice (the second
+ # execution does not remove any more tags).
+ strip_tags_depth = 0
while '<' in value and '>' in value:
+ if strip_tags_depth >= MAX_STRIP_TAGS_DEPTH:
+ raise SuspiciousOperation
new_value = _strip_once(value)
if value.count('<') == new_value.count('<'):
# _strip_once wasn't able to detect more tags.
break
value = new_value
+ strip_tags_depth += 1
return value
diff --git a/tests/utils_tests/test_html.py b/tests/utils_tests/test_html.py
index 8fe2f24..2f412e1 100644
--- a/tests/utils_tests/test_html.py
+++ b/tests/utils_tests/test_html.py
@@ -1,6 +1,7 @@
import os
from datetime import datetime
+from django.core.exceptions import SuspiciousOperation
from django.test import SimpleTestCase
from django.utils.functional import lazystr
from django.utils.html import (
@@ -90,12 +91,18 @@ class TestUtilsHtml(SimpleTestCase):
('<script>alert()</script>&h', 'alert()h'),
('><!' + ('&' * 16000) + 'D', '><!' + ('&' * 16000) + 'D'),
('X<<<<br>br>br>br>X', 'XX'),
+ ("<" * 50 + "a>" * 50, ""),
)
for value, output in items:
with self.subTest(value=value, output=output):
self.check_output(strip_tags, value, output)
self.check_output(strip_tags, lazystr(value), output)
+ def test_strip_tags_suspicious_operation(self):
+ value = "<" * 51 + "a>" * 51, "<a>"
+ with self.assertRaises(SuspiciousOperation):
+ strip_tags(value)
+
def test_strip_tags_files(self):
# Test with more lengthy content (also catching performance regressions)
for filename in ('strip_tags1.html', 'strip_tags2.txt'):
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