CVE-2024-45230: Django Template Filter DoS Vulnerability

CVE-2024-45230 Overview

CVE-2024-45230 is a Denial of Service vulnerability affecting Django, the popular Python web framework. The vulnerability exists in the urlize() and urlizetrunc() template filters, which are susceptible to algorithmic complexity attacks when processing very large inputs containing specific character sequences. An attacker can exploit this vulnerability to cause resource exhaustion and denial of service on affected Django applications.

Critical Impact

Unauthenticated remote attackers can send specially crafted input to trigger excessive CPU consumption, potentially rendering Django applications unresponsive and impacting service availability.

Affected Products

• Django 5.1 (before 5.1.1)
• Django 5.0 (before 5.0.9)
• Django 4.2 (before 4.2.16)

Discovery Timeline

• September 3, 2024 - Django Project releases security patches
• October 8, 2024 - CVE-2024-45230 published to NVD
• March 17, 2025 - Last updated in NVD database

Technical Details for CVE-2024-45230

Vulnerability Analysis

The urlize() and urlizetrunc() template filters in Django are designed to convert URLs and email addresses in plain text into clickable links. These filters parse input strings to identify URL patterns and wrap them in appropriate HTML anchor tags.

The vulnerability arises from inefficient algorithmic handling of certain input patterns. When processing very large inputs containing specific character sequences, the parsing logic exhibits poor time complexity, leading to excessive CPU consumption. This algorithmic complexity vulnerability allows attackers to craft malicious inputs that consume disproportionate server resources relative to input size.

The vulnerability can be exploited remotely over the network without requiring authentication or user interaction. While the attack does not compromise data confidentiality or integrity, it can severely impact application availability by exhausting server resources.

Root Cause

The root cause is insufficient input validation and algorithmic inefficiency in the URL pattern matching logic within the urlize() and urlizetrunc() template filters. When these filters encounter large inputs with specific character patterns, the parsing algorithm's performance degrades significantly, creating conditions for resource exhaustion attacks.

Attack Vector

The attack vector is network-based, targeting Django applications that use the urlize() or urlizetrunc() template filters to process user-controlled input. An attacker can submit specially crafted strings through any input field, form submission, API endpoint, or other data entry point that feeds into templates utilizing these vulnerable filters.

The attack does not require authentication, making any publicly accessible Django application that processes user input through these filters a potential target. The specific character sequences that trigger the vulnerability exploit the filter's URL detection algorithm, causing it to perform excessive computations.

Detection Methods for CVE-2024-45230

Indicators of Compromise

• Abnormally high CPU utilization on Django application servers
• Increased response times or timeouts for web requests
• Large HTTP request payloads containing repetitive or unusual character sequences
• Application logs showing slow template rendering times
• Memory consumption spikes during request processing

Detection Strategies

• Monitor application performance metrics for unusual CPU consumption patterns
• Implement request size limits and input validation at the application edge
• Review application templates to identify usage of urlize() and urlizetrunc() filters
• Enable Django debug logging to identify slow template rendering operations
• Deploy web application firewalls (WAF) with rules to detect unusually large text inputs

Monitoring Recommendations

• Configure alerting for sustained high CPU usage on web application servers
• Monitor request processing times and set thresholds for anomaly detection
• Track request payload sizes and flag unusually large text submissions
• Implement application-level rate limiting to prevent abuse
• Use SentinelOne Singularity platform to monitor for resource exhaustion patterns and anomalous process behavior

How to Mitigate CVE-2024-45230

Immediate Actions Required

• Upgrade Django to patched versions: 5.1.1, 5.0.9, or 4.2.16 immediately
• Audit templates to identify all uses of urlize() and urlizetrunc() filters
• Implement input length validation before data reaches template rendering
• Consider temporarily disabling affected template filters until patching is complete
• Deploy rate limiting at the load balancer or WAF level

Patch Information

Django has released security patches addressing this vulnerability in the following versions:

• Django 5.1.1 (fixes Django 5.1 series)
• Django 5.0.9 (fixes Django 5.0 series)
• Django 4.2.16 (fixes Django 4.2 LTS series)

Organizations should upgrade to these patched versions immediately. For detailed information, refer to the Django Security Release Blog and the Django Security Release Notes.

Workarounds

• Implement strict input length limits on any user-controlled data that may be processed by urlize() or urlizetrunc() filters
• Add custom template tags that validate input size before calling the vulnerable filters
• Deploy a web application firewall (WAF) to filter requests with excessively large payloads
• Use rate limiting to prevent rapid submission of potential DoS payloads
• Consider removing or replacing usage of these filters with alternative URL detection methods

# Upgrade Django to patched version
pip install --upgrade Django>=5.1.1
# Or for 5.0 series
pip install --upgrade 'Django>=5.0.9,<5.1'
# Or for 4.2 LTS series
pip install --upgrade 'Django>=4.2.16,<5.0'

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