Urllib3, a widely used Python library for HTTP clients, has been found to be vulnerable to a denial of service attack due to an inefficient method in its request processing logic. This vulnerability was discovered in version 1.25.2 and could potentially allow an attacker to consume excessive CPU resources, leading to a denial of service. To mitigate this risk, users are advised to update their urllib3 version to the latest current version (1.25.8) or use tools like Snyk to check for vulnerabilities in their dependencies. The vulnerability was addressed in later versions of urllib3, and Snyk offers free tier scans for open source projects and private repositories to help developers identify and remediate vulnerabilities.