[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>

1 files changed, 7 insertions, 6 deletions

diff --git a/django/contrib/humanize/templatetags/humanize.py b/django/contrib/humanize/templatetags/humanize.py
index 23224779c5..2c26f8944a 100644
--- a/django/contrib/humanize/templatetags/humanize.py
+++ b/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)
-    new = re.sub(r"^(-?\d+)(\d{3})", r"\g<1>,\g<2>", orig)
-    if orig == new:
-        return new
-    else:
-        return intcomma(new, use_l10n)
+    result = str(value)
+    match = re.match(r"-?\d+", result)
+    if match:
+        prefix = match[0]
+        prefix_with_commas = re.sub(r"\d{3}", r"\g<0>,", prefix[::-1])[::-1]
+        result = prefix_with_commas + result[len(prefix) :]
+    return result
 
 
 # A tuple of standard large number to their converters