CVE-2025-14550: Django ASGIRequest DOS Vulnerability

CVE-2025-14550 Overview

A denial-of-service vulnerability has been identified in Django's ASGIRequest handler that allows remote attackers to exhaust server resources through specially crafted HTTP requests containing multiple duplicate headers. This vulnerability affects Django versions 6.0 before 6.0.2, 5.2 before 5.2.11, and 4.2 before 4.2.28, with earlier unsupported series (5.0.x, 4.1.x, and 3.2.x) potentially also vulnerable.

Critical Impact

Remote attackers can cause denial-of-service conditions on Django ASGI applications without authentication, potentially rendering web services unavailable to legitimate users.

Affected Products

• Django 6.0 through 6.0.1
• Django 5.2 through 5.2.10
• Django 4.2 through 4.2.27

Discovery Timeline

• 2026-02-03 - CVE CVE-2025-14550 published to NVD
• 2026-02-03 - Django Project releases security patch
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2025-14550

Vulnerability Analysis

The vulnerability resides in Django's ASGI (Asynchronous Server Gateway Interface) request handling mechanism. When processing incoming HTTP requests, the ASGIRequest class fails to properly limit or efficiently handle scenarios where an attacker sends requests with numerous duplicate HTTP headers. This inefficient algorithmic complexity (CWE-407) allows attackers to consume disproportionate server resources with relatively small request payloads.

ASGI is Django's interface for handling asynchronous web requests, commonly used with deployment servers like Daphne, Uvicorn, or Hypercorn. Applications deployed using ASGI configurations are susceptible to this attack, while traditional WSGI deployments may not be affected.

Root Cause

The root cause is classified as CWE-407 (Inefficient Algorithmic Complexity). The ASGIRequest header parsing implementation does not impose adequate limits on processing duplicate headers, allowing malicious requests to trigger resource-intensive operations. When multiple headers with the same name are present in a request, the parsing logic may perform redundant processing operations that scale poorly, leading to CPU exhaustion or memory consumption on the server.

Attack Vector

The attack can be executed remotely over the network without any authentication requirements. An attacker constructs HTTP requests containing a large number of duplicate headers and sends them to a vulnerable Django ASGI application. The server processes these headers inefficiently, consuming CPU cycles and potentially memory. By sending multiple such requests, an attacker can overwhelm the server's capacity to handle legitimate traffic.

The attack requires no user interaction and can be automated to maintain sustained pressure on target systems. Due to the network-accessible nature of web applications, this vulnerability poses a significant risk to internet-facing Django deployments using ASGI.

Detection Methods for CVE-2025-14550

Indicators of Compromise

• Unusual HTTP requests with abnormally large header sections or high header counts
• Sudden spikes in CPU utilization on ASGI worker processes
• Increased memory consumption by Django application processes
• Elevated request latency or timeouts for legitimate users

Detection Strategies

• Monitor HTTP request patterns for anomalous header counts exceeding normal thresholds
• Configure web application firewalls (WAF) to detect and block requests with excessive duplicate headers
• Implement rate limiting on incoming connections to mitigate automated attack attempts
• Analyze ASGI server logs for patterns indicative of header-based DoS attempts

Monitoring Recommendations

• Set up alerting for abnormal resource consumption on application servers
• Monitor connection counts and request rates to identify potential DoS attacks in progress
• Review application performance metrics for degradation patterns consistent with resource exhaustion
• Implement distributed tracing to identify slow request patterns caused by header processing

How to Mitigate CVE-2025-14550

Immediate Actions Required

• Upgrade Django to patched versions: 6.0.2, 5.2.11, or 4.2.28 depending on your current series
• Review deployment configurations to ensure ASGI servers have appropriate timeout and connection limits
• Enable rate limiting at the reverse proxy or load balancer level
• Consider implementing request header validation at the edge (nginx, Apache, or CDN)

Patch Information

Django has released security patches addressing this vulnerability. Organizations should upgrade to the following minimum versions:

For detailed patch information, refer to the Django Security Releases announcement. Additional security release notes are available in the Django Security Release Notes.

Workarounds

• Deploy a reverse proxy (nginx, HAProxy) configured to limit header count and size before requests reach Django
• Implement request filtering at the WAF level to reject requests with excessive duplicate headers
• Consider temporarily switching to WSGI deployment if ASGI is not strictly required while patching is in progress
• Apply network-level rate limiting to reduce the impact of automated attack attempts

# Example nginx configuration to limit header processing
# Add to server or location block
large_client_header_buffers 4 8k;
client_header_buffer_size 1k;

# Limit connections per IP
limit_conn_zone $binary_remote_addr zone=conn_limit:10m;
limit_conn conn_limit 10;

# Rate limiting
limit_req_zone $binary_remote_addr zone=req_limit:10m rate=10r/s;
limit_req zone=req_limit burst=20 nodelay;