CVE-2024-52804 is a vulnerability classified under CWE-400 (Uncontrolled Resource Consumption) and CWE-770 (Allocation of Resources Without Limits or Throttling) affecting the Tornado web framework, a popular Python asynchronous networking library. The root cause is an inefficient algorithm used for parsing HTTP cookies in Tornado versions earlier than 6.4.2. Specifically, the cookie parsing algorithm exhibits quadratic time complexity under certain crafted inputs, meaning that the CPU time required grows disproportionately with the size or complexity of the cookie header. An attacker can exploit this by sending specially crafted HTTP cookie headers that cause the Tornado server's event loop thread to consume excessive CPU resources. Since the parsing occurs in the event loop thread, this leads to blocking or significant delays in processing other incoming requests, effectively causing a denial-of-service (DoS) condition. The vulnerability can be triggered remotely without any authentication or user interaction, increasing its risk profile. Although no public exploits have been observed in the wild yet, the high CVSS score of 7.5 reflects the potential impact. The fix involves updating Tornado to version 6.4.2, where the parsing algorithm has been optimized or replaced to prevent quadratic complexity and resource exhaustion. This vulnerability is particularly critical for high-traffic Tornado-based web services where availability and responsiveness are essential.

For European organizations, the impact of CVE-2024-52804 can be significant, especially for those relying on Tornado for web applications, APIs, or asynchronous services. The vulnerability can lead to denial-of-service conditions by exhausting CPU resources, resulting in service outages or degraded performance. This can disrupt business operations, cause loss of customer trust, and potentially lead to financial losses. Public-facing services are particularly vulnerable to remote exploitation without authentication, increasing the risk of widespread disruption. Organizations in sectors such as finance, e-commerce, healthcare, and government, which often require high availability and handle sensitive data, may face operational and reputational damage. Additionally, the blocking of the event loop thread can affect the scalability and responsiveness of applications, impacting user experience and service level agreements. While no direct confidentiality or integrity impact is reported, the availability impact alone justifies urgent remediation.

European organizations should take immediate action to mitigate this vulnerability by upgrading all Tornado deployments to version 6.4.2 or later, where the issue is resolved. For environments where immediate upgrading is not feasible, implementing network-level protections such as rate limiting or filtering suspicious HTTP cookie headers can reduce exposure. Monitoring CPU usage and application performance metrics can help detect anomalous spikes indicative of exploitation attempts. Application-layer firewalls or Web Application Firewalls (WAFs) should be configured to inspect and block malformed or excessively large cookie headers. Developers should review and test their Tornado-based applications to ensure they do not rely on vulnerable versions. Additionally, organizations should maintain an inventory of Tornado usage across their infrastructure to identify affected systems. Regular patch management and vulnerability scanning processes should be enforced to prevent similar risks. Finally, incident response plans should be updated to include detection and mitigation strategies for resource exhaustion attacks targeting asynchronous frameworks.