CVE-2023-24998 is a resource allocation vulnerability classified under CWE-770 affecting Apache Commons FileUpload versions before 1.5. The core issue is the lack of limits on the number of request parts processed during file uploads, which can be exploited by an attacker to overwhelm server resources by sending a large number of multipart requests or malicious uploads. This absence of throttling means that the server can consume excessive memory and CPU, leading to denial-of-service conditions. The vulnerability stems from the default configuration where the new setting FileUploadBase#setFileCountMax, designed to limit the number of file parts processed, is not enabled by default and must be explicitly set by administrators. Without this limit, attackers can craft requests that cause the server to allocate resources uncontrollably. Although no known exploits are currently reported in the wild, the vulnerability presents a significant risk for web applications using this library, especially those exposed to untrusted users or the internet. The lack of authentication or user interaction requirements makes exploitation straightforward. The vulnerability affects a wide range of applications since Apache Commons FileUpload is a common Java library for handling file uploads in web applications. The absence of a CVSS score necessitates an assessment based on impact and exploitability factors.

For European organizations, this vulnerability poses a risk of denial-of-service attacks against web applications that utilize vulnerable versions of Apache Commons FileUpload. Such attacks can disrupt business operations, degrade service availability, and potentially cause downtime for critical services. Organizations in sectors such as finance, government, healthcare, and e-commerce, which often rely on Java-based web applications, may experience significant operational impacts. The disruption could affect customer-facing portals, internal tools, or APIs that handle file uploads. Additionally, the resource exhaustion could lead to cascading failures in shared infrastructure environments, impacting multiple services. Given the ease of exploitation without authentication or user interaction, attackers can launch automated attacks at scale. This could also increase the risk of reputational damage and regulatory scrutiny under European data protection laws if service availability is compromised.

To mitigate this vulnerability, organizations should upgrade Apache Commons FileUpload to version 1.5 or later where the issue is addressed. If immediate upgrade is not feasible, administrators must explicitly configure the FileUploadBase#setFileCountMax parameter to impose strict limits on the number of file parts processed per request, thereby preventing resource exhaustion. It is critical to review and harden file upload handling logic to include additional validation and rate limiting at the application or web server level. Deploying web application firewalls (WAFs) with rules to detect and block abnormal multipart requests can provide an additional layer of defense. Monitoring for unusual spikes in multipart upload requests and resource usage can help detect exploitation attempts early. Finally, incorporating robust logging and alerting mechanisms for file upload anomalies will aid in rapid incident response.