[4.2.x] Fixed CVE-2024-24680 -- Mitigated potential DoS in intcomma template filter.

Thanks Seokchan Yoon for the report.

Co-authored-by: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Co-authored-by: Natalia <124304+nessita@users.noreply.github.com>
Co-authored-by: Shai Berger <shai@platonix.com>

django/contrib/humanize/templatetags/humanize.py

@@ -75,12 +75,13 @@ def intcomma(value, use_l10n=True):
             return intcomma(value, False)
         else:
             return number_format(value, use_l10n=True, force_grouping=True)
-    orig = str(value)
+    result = str(value)
-    new = re.sub(r"^(-?\d+)(\d{3})", r"\g<1>,\g<2>", orig)
+    match = re.match(r"-?\d+", result)
-    if orig == new:
+    if match:
-        return new
+        prefix = match[0]
-    else:
+        prefix_with_commas = re.sub(r"\d{3}", r"\g<0>,", prefix[::-1])[::-1]
-        return intcomma(new, use_l10n)
+        result = prefix_with_commas + result[len(prefix) :]
+    return result
 
 
 # A tuple of standard large number to their converters

docs/releases/3.2.24.txt

@@ -6,4 +6,8 @@ Django 3.2.24 release notes
 
 Django 3.2.24 fixes a security issue with severity "moderate" in 3.2.23.
 
-...
+CVE-2024-24680: Potential denial-of-service in ``intcomma`` template filter
+===========================================================================
+
+The ``intcomma`` template filter was subject to a potential denial-of-service
+attack when used with very long strings.

docs/releases/4.2.10.txt

@@ -6,4 +6,8 @@ Django 4.2.10 release notes
 
 Django 4.2.10 fixes a security issue with severity "moderate" in 4.2.9.
 
-...
+CVE-2024-24680: Potential denial-of-service in ``intcomma`` template filter
+===========================================================================
+
+The ``intcomma`` template filter was subject to a potential denial-of-service
+attack when used with very long strings.

tests/humanize_tests/tests.py

@@ -116,39 +116,71 @@ class HumanizeTests(SimpleTestCase):
     def test_intcomma(self):
         test_list = (
             100,
+            -100,
             1000,
+            -1000,
             10123,
+            -10123,
             10311,
+            -10311,
             1000000,
+            -1000000,
             1234567.25,
+            -1234567.25,
             "100",
+            "-100",
             "1000",
+            "-1000",
             "10123",
+            "-10123",
             "10311",
+            "-10311",
             "1000000",
+            "-1000000",
             "1234567.1234567",
+            "-1234567.1234567",
             Decimal("1234567.1234567"),
+            Decimal("-1234567.1234567"),
             None,
             "１２３４５６７",
+            "-１２３４５６７",
             "１２３４５６７.１２",
+            "-１２３４５６７.１２",
+            "the quick brown fox jumped over the lazy dog",
         )
         result_list = (
             "100",
+            "-100",
             "1,000",
+            "-1,000",
             "10,123",
+            "-10,123",
             "10,311",
+            "-10,311",
             "1,000,000",
+            "-1,000,000",
             "1,234,567.25",
+            "-1,234,567.25",
             "100",
+            "-100",
             "1,000",
+            "-1,000",
             "10,123",
+            "-10,123",
             "10,311",
+            "-10,311",
             "1,000,000",
+            "-1,000,000",
             "1,234,567.1234567",
+            "-1,234,567.1234567",
             "1,234,567.1234567",
+            "-1,234,567.1234567",
             None,
             "1,234,567",
+            "-1,234,567",
             "１,２３４,５６７.１２",
+            "-１,２３４,５６７.１２",
+            "the quick brown fox jumped over the lazy dog",
         )
         with translation.override("en"):
             self.humanize_tester(test_list, result_list, "intcomma")
@@ -156,39 +188,71 @@ class HumanizeTests(SimpleTestCase):
     def test_l10n_intcomma(self):
         test_list = (
             100,
+            -100,
             1000,
+            -1000,
             10123,
+            -10123,
             10311,
+            -10311,
             1000000,
+            -1000000,
             1234567.25,
+            -1234567.25,
             "100",
+            "-100",
             "1000",
+            "-1000",
             "10123",
+            "-10123",
             "10311",
+            "-10311",
             "1000000",
+            "-1000000",
             "1234567.1234567",
+            "-1234567.1234567",
             Decimal("1234567.1234567"),
+            -Decimal("1234567.1234567"),
             None,
             "１２３４５６７",
+            "-１２３４５６７",
             "１２３４５６７.１２",
+            "-１２３４５６７.１２",
+            "the quick brown fox jumped over the lazy dog",
         )
         result_list = (
             "100",
+            "-100",
             "1,000",
+            "-1,000",
             "10,123",
+            "-10,123",
             "10,311",
+            "-10,311",
             "1,000,000",
+            "-1,000,000",
             "1,234,567.25",
+            "-1,234,567.25",
             "100",
+            "-100",
             "1,000",
+            "-1,000",
             "10,123",
+            "-10,123",
             "10,311",
+            "-10,311",
             "1,000,000",
+            "-1,000,000",
             "1,234,567.1234567",
+            "-1,234,567.1234567",
             "1,234,567.1234567",
+            "-1,234,567.1234567",
             None,
             "1,234,567",
+            "-1,234,567",
             "１,２３４,５６７.１２",
+            "-１,２３４,５６７.１２",
+            "the quick brown fox jumped over the lazy dog",
         )
         with self.settings(USE_THOUSAND_SEPARATOR=False):
             with translation.override("en"):