CVE-2026-3816 is a denial of service vulnerability affecting OWASP DefectDojo versions 2.55.0 through 2.55.4. The vulnerability resides in the input_zip.read function of the parser.py file, specifically within the SonarQubeParser/MSDefenderParser component. This function processes input ZIP files, and improper handling or manipulation of these inputs can cause the application to crash or become unresponsive, resulting in denial of service. The vulnerability can be triggered remotely without requiring authentication or user interaction, increasing the risk of exploitation. The CVSS 4.0 base score is 5.3 (medium severity), reflecting the ease of remote exploitation and the impact limited to availability disruption. The vulnerability does not affect confidentiality or integrity. The patch for this issue is included in DefectDojo version 2.56.0, identified by commit e8f1e5131535b8fd80a7b1b3085d676295fdcd41. No known exploits have been observed in the wild, but the public disclosure increases the likelihood of potential attacks. DefectDojo is an open-source security orchestration, automation, and response (SOAR) tool widely used by security teams to manage vulnerabilities and security testing workflows. Disruption of DefectDojo services can impede vulnerability management processes and delay security operations. The vulnerability highlights the importance of validating and safely parsing external input files to prevent service disruption.

The primary impact of CVE-2026-3816 is denial of service, which can cause DefectDojo instances to crash or become unresponsive. This disrupts security teams' ability to manage and track vulnerabilities, potentially delaying remediation efforts and increasing organizational risk exposure. Since DefectDojo is often integrated into security pipelines and used for vulnerability aggregation and reporting, its unavailability can impair incident response and compliance activities. The vulnerability does not lead to data leakage or integrity compromise, but availability loss in security tooling can indirectly increase risk by hindering timely vulnerability management. Organizations relying heavily on DefectDojo for security orchestration may experience operational downtime, impacting their overall security posture. The ease of remote exploitation without authentication means attackers can potentially launch DoS attacks from external networks, increasing the threat surface. However, the lack of known exploits in the wild suggests limited active targeting so far. Prompt patching is critical to avoid service interruptions and maintain continuous security operations.

To mitigate CVE-2026-3816, organizations should upgrade OWASP DefectDojo to version 2.56.0 or later, which contains the official patch for this vulnerability. Until the upgrade is applied, administrators should consider restricting access to DefectDojo instances, especially the components handling ZIP file inputs, to trusted networks or VPNs to reduce exposure. Implement network-level protections such as Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) to detect and block malformed or suspicious ZIP file uploads targeting the vulnerable parser. Monitoring application logs for unusual errors or crashes related to ZIP file processing can provide early detection of exploitation attempts. Additionally, security teams should review and harden input validation and parsing logic in custom integrations or extensions that interact with DefectDojo parsers. Regularly auditing and updating all components of the security toolchain will help prevent similar vulnerabilities. Finally, maintain an incident response plan that includes procedures for handling denial of service incidents affecting security infrastructure.