CVE-2024-56374: Django IPv6 Validation DoS Vulnerability

CVE-2024-56374 Overview

An issue was discovered in Django 5.1 before 5.1.5, 5.0 before 5.0.11, and 4.2 before 4.2.18. Lack of upper-bound limit enforcement in strings passed when performing IPv6 validation could lead to a potential denial-of-service attack. The undocumented and private functions clean_ipv6_address and is_valid_ipv6_address are vulnerable, as is the django.forms.GenericIPAddressField form field. (The django.db.models.GenericIPAddressField model field is not affected.)

Critical Impact

This vulnerability allows remote attackers to cause a denial-of-service condition by sending specially crafted, excessively long strings to IPv6 validation functions in Django applications, potentially exhausting server resources and making applications unresponsive.

Affected Products

• Django 5.1 before 5.1.5
• Django 5.0 before 5.0.11
• Django 4.2 before 4.2.18
• Debian Linux 11.0

Discovery Timeline

• 2025-01-14 - Django releases security patches and publishes security advisory
• 2025-01-14 - CVE CVE-2024-56374 published to NVD
• 2025-10-03 - Last updated in NVD database

Technical Details for CVE-2024-56374

Vulnerability Analysis

This vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) exists in Django's IPv6 validation functionality. The core issue is the absence of an upper-bound limit on the length of strings accepted by the IPv6 validation functions. When processing IPv6 address strings, the affected functions do not enforce reasonable input length constraints, allowing attackers to submit arbitrarily long strings that consume excessive computational resources during validation.

The vulnerable components include the undocumented private functions clean_ipv6_address and is_valid_ipv6_address, as well as the public django.forms.GenericIPAddressField form field. It's important to note that the django.db.models.GenericIPAddressField model field is NOT affected by this vulnerability.

Root Cause

The root cause is improper resource allocation handling in Django's IPv6 validation logic. The validation functions fail to implement upper-bound checks on input string lengths before processing them. This oversight allows maliciously crafted, excessively long input strings to be processed, consuming disproportionate server resources. The lack of input length validation before performing computationally intensive IPv6 parsing operations creates the denial-of-service condition.

Attack Vector

An attacker can exploit this vulnerability remotely over the network without requiring authentication or user interaction. The attack involves submitting specially crafted, extremely long strings to any Django form field or function that performs IPv6 validation using the affected components. When the application attempts to validate these oversized strings, server resources become exhausted, potentially leading to application unavailability.

The vulnerability is exploited through form submissions to Django applications using GenericIPAddressField or through any code path that calls the private clean_ipv6_address or is_valid_ipv6_address functions with user-controlled input.

Detection Methods for CVE-2024-56374

Indicators of Compromise

• Unusual spikes in CPU usage on Django application servers during form processing
• Abnormally long HTTP POST requests targeting forms with IP address fields
• Application timeouts or unresponsiveness coinciding with form submission activity
• Log entries showing excessively long string inputs in IP address form fields

Detection Strategies

• Monitor application performance metrics for sudden resource exhaustion patterns during form processing
• Implement web application firewall (WAF) rules to detect and block requests with unusually large payloads targeting IP address fields
• Review application logs for failed validation attempts with exceptionally long input strings
• Set up alerting for Django application response time degradation

Monitoring Recommendations

• Configure infrastructure monitoring to alert on abnormal CPU and memory consumption patterns
• Implement request rate limiting on form submission endpoints
• Enable detailed logging for form validation failures to capture potential exploitation attempts
• Monitor network traffic for patterns indicative of denial-of-service attacks targeting web forms

How to Mitigate CVE-2024-56374

Immediate Actions Required

• Upgrade Django to version 5.1.5, 5.0.11, or 4.2.18 immediately depending on your installed version
• Audit your Django applications to identify usage of GenericIPAddressField in forms
• Implement input length validation at the application or WAF level as a temporary measure before patching
• Review and restrict access to any endpoints accepting IP address input

Patch Information

Django has released security patches addressing this vulnerability:

• Django 5.1.5 - Patched version for Django 5.1.x series
• Django 5.0.11 - Patched version for Django 5.0.x series
• Django 4.2.18 - Patched version for Django 4.2.x LTS series

For detailed patch information, refer to the Django Security Release Notes and the Django Weblog Security Updates. Debian users should consult the Debian LTS Security Announcement.

Workarounds

• Implement custom input validation to reject IP address strings exceeding reasonable length limits (IPv6 addresses should not exceed 45 characters)
• Deploy a web application firewall (WAF) with rules to limit input payload sizes for form fields
• Add rate limiting on form submission endpoints to mitigate resource exhaustion attempts
• Consider replacing django.forms.GenericIPAddressField with custom form fields that include length validation until patching is complete

# Upgrade Django to patched version
pip install --upgrade Django>=5.1.5

# Verify installed version
python -c "import django; print(django.VERSION)"