CVE-2025-48976 is a vulnerability in the Apache Commons FileUpload library, a widely used Java component for handling file uploads in web applications. The issue stems from the allocation of resources for multipart headers without imposing sufficient limits, classified under CWE-770 (Allocation of Resources Without Limits or Throttling). This flaw allows an unauthenticated remote attacker to send specially crafted multipart requests that cause the application to allocate excessive memory or processing resources, leading to denial-of-service (DoS) conditions. Affected versions include all releases from 1.0 up to but not including 1.6, and from 2.0.0-M1 up to but not including 2.0.0-M4. The vulnerability does not impact confidentiality or integrity but severely affects availability by exhausting server resources, potentially causing application crashes or unresponsiveness. Exploitation requires no user interaction and can be performed remotely over the network, increasing the risk profile. Although no known exploits have been reported in the wild, the vulnerability’s characteristics and the popularity of Apache Commons FileUpload in enterprise and public sector Java applications make it a critical issue. The recommended mitigation is to upgrade to versions 1.6 or 2.0.0-M4 where the issue has been fixed. Additional mitigations include implementing strict resource limits at the application or web server level and monitoring for abnormal multipart request patterns.

The primary impact of CVE-2025-48976 is denial of service, which can disrupt business operations by making web applications unavailable. For European organizations, this can lead to significant operational downtime, especially for critical services relying on Java-based web applications that use Apache Commons FileUpload. Public sector entities, financial institutions, and large enterprises with high availability requirements are particularly vulnerable. The lack of confidentiality or integrity impact means data breaches are unlikely, but service outages can cause reputational damage, regulatory scrutiny, and financial losses. Given the remote, unauthenticated nature of the exploit, attackers can target exposed web applications at scale, potentially causing widespread disruption. The vulnerability could also be leveraged as part of a larger attack chain to distract or exhaust resources while other attacks are conducted. Organizations in Europe with extensive Java application deployments must assess their exposure and prioritize remediation to maintain service continuity.

1. Upgrade Apache Commons FileUpload to version 1.6 or 2.0.0-M4 or later immediately to apply the official fix. 2. Implement strict limits on multipart header sizes and total request sizes at the application or web server level to prevent resource exhaustion. 3. Deploy web application firewalls (WAFs) with rules to detect and block abnormal multipart/form-data requests indicative of DoS attempts. 4. Monitor application and server resource usage closely for spikes that may indicate exploitation attempts. 5. Conduct regular vulnerability scans and dependency checks to identify usage of vulnerable library versions. 6. For legacy systems where immediate upgrade is not feasible, consider isolating vulnerable services behind network controls and rate limiting to reduce exposure. 7. Educate development teams on secure file upload handling and resource management best practices to prevent similar issues in future software. 8. Maintain incident response plans that include detection and mitigation strategies for DoS attacks targeting web application components.