CVE-2019-12406 in CXF
Summary
by MITRE
Apache CXF before 3.3.4 and 3.2.11 does not restrict the number of message attachments present in a given message. This leaves open the possibility of a denial of service type attack, where a malicious user crafts a message containing a very large number of message attachments. From the 3.3.4 and 3.2.11 releases, a default limit of 50 message attachments is enforced. This is configurable via the message property "attachment-max-count".
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Analysis
by VulDB Data Team • 11/07/2019
The vulnerability described in CVE-2019-12406 represents a critical denial of service weakness in Apache CXF web services framework versions prior to 3.3.4 and 3.2.11. This flaw stems from the absence of proper validation mechanisms to control the quantity of message attachments that can be processed within a single SOAP message. The vulnerability allows malicious actors to exploit this weakness by crafting specially designed messages containing an excessive number of attachments, potentially leading to system resource exhaustion and service disruption. The issue affects the core message processing capabilities of the framework, making it a significant concern for organizations relying on CXF for their web service implementations.
The technical root cause of this vulnerability lies in the lack of attachment count validation within the message processing pipeline of Apache CXF. When a message arrives at the server, the framework processes all attachments without imposing any limits on their number, creating an opportunity for attackers to overwhelm the system resources. This flaw is categorized under CWE-400, which specifically addresses "Uncontrolled Resource Consumption" or "Resource Exhaustion" vulnerabilities. The absence of this restriction means that a single malicious message could consume excessive memory, CPU cycles, and other system resources, effectively rendering the affected services unavailable to legitimate users. The vulnerability demonstrates poor input validation practices and highlights the importance of implementing resource limits in network service applications.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire infrastructure availability. Attackers can leverage this weakness to perform resource exhaustion attacks that consume memory, disk space, and processing power at an accelerated rate. In enterprise environments where CXF services handle critical business operations, such an attack could lead to significant financial losses, service degradation, and reputational damage. The vulnerability affects both the 3.2.x and 3.3.x release lines of Apache CXF, indicating it was present across multiple versions and likely affected a substantial portion of the user base. Organizations running vulnerable versions face increased risk of denial of service attacks that could be difficult to detect and mitigate due to their resource-intensive nature.
The mitigation strategy for CVE-2019-12406 involves upgrading to Apache CXF versions 3.3.4 or 3.2.11, which introduced a default limit of 50 message attachments per message. This default setting provides reasonable protection against typical resource exhaustion attacks while allowing legitimate applications to function normally. Administrators can further customize the protection by configuring the "attachment-max-count" message property to suit specific operational requirements. This approach aligns with the principle of defense in depth as outlined in the MITRE ATT&CK framework, where multiple layers of protection are implemented to prevent or mitigate attacks. The solution demonstrates proper input validation and resource management practices that are essential for maintaining service availability in web service environments. Organizations should also implement monitoring and alerting mechanisms to detect unusual attachment counts in their services, providing additional protection against potential exploitation attempts.