AIOHTTP Infinite Loop Vulnerability in POST Body Processing Allowing Denial-of-Service

A denial-of-service vulnerability has been identified in AIOHTTP, an asynchronous HTTP client/server framework for Python. This issue affects versions 3.13.2 and earlier. The vulnerability arises when assert statements are bypassed, leading to an infinite loop while processing the body of POST requests. If Python optimizations are enabled and the application includes a handler that utilizes the Request.post() method, an attacker could exploit this vulnerability with a specially crafted message, causing a DoS condition.

Impact

Exploiting this vulnerability can lead to a denial-of-service condition, where the application becomes unresponsive or fails to process requests properly.

Reproduction

To reproduce this vulnerability, first ensure that Python optimizations are enabled, either by using the -O flag or setting the PYTHONOPTIMIZE environment variable to 1. Then, create an AIOHTTP server application that includes a handler using the Request.post() method. Send a POST request with a crafted message that bypasses the usual assertion checks. The server should enter an infinite loop, demonstrating the denial-of-service condition.

Remediation

Users can upgrade to AIOHTTP version 3.13.3 or later, where this vulnerability has been fixed.