CVE-2024-39614 Overview
CVE-2024-39614 is a denial-of-service vulnerability affecting Django 5.0 before 5.0.7 and Django 4.2 before 4.2.14. The flaw resides in the get_supported_language_variant() function, which becomes computationally expensive when processing very long strings containing specific characters. A remote unauthenticated attacker can submit crafted input to trigger excessive resource consumption and make the application unresponsive.
The vulnerability is categorized under [CWE-130] (Improper Handling of Length Parameter Inconsistency). It carries a network attack vector with no authentication or user interaction required, making it accessible to any client able to reach the affected Django endpoints.
Critical Impact
Unauthenticated attackers can remotely exhaust server resources on vulnerable Django deployments by sending crafted language variant strings, disrupting service availability.
Affected Products
- Django 5.0 before 5.0.7
- Django 4.2 before 4.2.14
- Applications and appliances bundling Django (see NetApp advisory NTAP-20240808-0005)
Discovery Timeline
- 2024-07-09 - Django project publishes security release advisory
- 2024-07-10 - CVE-2024-39614 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-39614
Vulnerability Analysis
The defect lives in Django's internationalization (i18n) machinery, specifically the get_supported_language_variant() helper in django.utils.translation. This function resolves a requested language code to a supported variant by parsing and normalizing the input. When the input contains pathological character sequences, the parsing routine performs work that scales poorly with input length.
An attacker who supplies an extremely long string with the right characters forces the function into a costly execution path. The resulting CPU consumption blocks the worker process and degrades or halts request handling for legitimate users.
Exploitation requires no credentials. Any endpoint that accepts a language hint, such as the Accept-Language header, the ?language= query parameter, or URL prefixes used by i18n_patterns, can serve as an entry point.
Root Cause
The root cause is improper handling of input length within the language-resolution routine. The function did not bound the size or normalize the structure of incoming language tags before performing string operations, allowing attacker-controlled length to drive disproportionate CPU work.
Attack Vector
Attackers send HTTP requests carrying oversized language identifiers to any Django view that consults get_supported_language_variant(). The function is invoked during middleware processing for i18n-enabled applications, so the vulnerable code path is reachable on the default request lifecycle. Repeated requests amplify the impact and produce a sustained denial-of-service condition.
The vulnerability mechanism is described in the Django Security Weblog Post and Django Security Release Notes. No public proof-of-concept code is required to reproduce the condition.
Detection Methods for CVE-2024-39614
Indicators of Compromise
- HTTP requests carrying unusually long Accept-Language headers or language parameters, particularly strings exceeding several hundred characters.
- Sustained high CPU utilization on Django worker processes correlated with inbound i18n-related requests.
- Increased request latency or worker pool exhaustion in WSGI or ASGI servers fronting Django.
Detection Strategies
- Inspect web server and reverse proxy logs for requests with abnormally long language identifiers and group them by source IP.
- Deploy a web application firewall (WAF) rule that flags Accept-Language header lengths exceeding a sensible threshold, for example 256 bytes.
- Correlate application performance monitoring (APM) traces showing time spent in django.utils.translation with the originating request headers.
Monitoring Recommendations
- Establish baselines for request header sizes and CPU usage per worker, and alert on deviations.
- Forward Nginx, HAProxy, or CDN access logs to a centralized analytics pipeline for retroactive hunts after the patch window.
- Track Django error rates and worker restart events, which often spike when DoS conditions occur.
How to Mitigate CVE-2024-39614
Immediate Actions Required
- Upgrade Django to version 5.0.7, 4.2.14, or later as specified in the Django Security Release Notes.
- Audit deployed Django versions across production, staging, and internal tooling, including container images and bundled appliances referenced in the NetApp Security Advisory NTAP-20240808-0005.
- Apply rate limiting at the edge for unauthenticated endpoints that process language headers.
Patch Information
The Django project released fixed versions 5.0.7 and 4.2.14 on July 9, 2024. The patches bound the input length and adjust parsing logic in get_supported_language_variant() to prevent disproportionate work. Details are documented in the Django Security Weblog Post.
Workarounds
- Configure a WAF or reverse proxy to reject requests with Accept-Language headers or language query parameters exceeding a fixed length.
- Disable LocaleMiddleware and i18n_patterns on applications that do not require internationalization until patching is complete.
- Apply per-IP request rate limiting on endpoints that exercise language negotiation.
# Configuration example: upgrade Django to a patched release
pip install --upgrade "Django>=4.2.14,<5.0" # for 4.2.x deployments
pip install --upgrade "Django>=5.0.7" # for 5.0.x deployments
python -c "import django; print(django.get_version())"
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