CVE-2016-20026 in ZKBioSecurity
Summary
by MITRE • 03/16/2026
ZKTeco ZKBioSecurity 3.0 contains hardcoded credentials in the bundled Apache Tomcat server that allow unauthenticated attackers to access the manager application. Attackers can authenticate with hardcoded credentials stored in tomcat-users.xml to upload malicious WAR archives containing JSP applications and execute arbitrary code with SYSTEM privileges.
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Analysis
by VulDB Data Team • 03/16/2026
The vulnerability identified as CVE-2016-20026 resides within the ZKTeco ZKBioSecurity 3.0 software platform, which is designed for biometric security management and access control systems. This particular weakness represents a critical security flaw that undermines the integrity of the entire security infrastructure by embedding default credentials directly within the application's configuration files. The affected system utilizes an embedded Apache Tomcat server that ships with hardcoded authentication credentials, creating a persistent backdoor that remains active regardless of system updates or configuration changes. This design decision violates fundamental security principles and creates an immediate attack surface that requires no prior authentication or exploitation knowledge from threat actors.
The technical implementation of this vulnerability involves the presence of hardcoded credentials within the tomcat-users.xml configuration file, which is a standard file used by Apache Tomcat to manage user authentication and authorization. These credentials are typically stored in plain text format and are intended for initial system setup rather than production deployment. However, in the ZKTeco implementation, these default credentials remain active and accessible throughout the system's operational lifecycle. The flaw enables attackers to authenticate directly with the manager application using these predetermined username and password combinations, bypassing any legitimate authentication mechanisms. This authentication bypass allows unauthorized access to the application management interface, which provides full administrative control over the Tomcat server.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it provides attackers with complete control over the underlying application server. Once authenticated, malicious actors can upload arbitrary WAR (Web Archive) files containing malicious JSP (Java Server Pages) applications that execute with SYSTEM privileges on the host machine. This privilege escalation capability allows attackers to perform actions such as modifying system configurations, accessing sensitive data, installing additional malware, or creating persistent backdoors within the network infrastructure. The implications are particularly severe for security systems that rely on ZKTeco devices, as these systems often contain sensitive biometric data, access logs, and network credentials that could be compromised through this vulnerability.
This vulnerability directly maps to CWE-798, which describes the use of hardcoded credentials in software applications, and represents a classic example of poor security configuration management. From an adversary perspective, this flaw aligns with ATT&CK technique T1078.004, which involves valid accounts used for lateral movement and privilege escalation. The attack surface created by this vulnerability is particularly concerning because it affects not just individual devices but entire security ecosystems that may rely on ZKTeco platforms for access control and biometric authentication. Organizations implementing these systems face significant risks including data breaches, unauthorized physical access, and potential compromise of critical infrastructure. The vulnerability demonstrates a fundamental failure in secure software development practices, where default configurations are not properly secured or disabled in production environments.
Mitigation strategies for this vulnerability require immediate action to address the hardcoded credentials issue and implement proper access controls. Organizations should first disable or remove the manager application from the embedded Tomcat server and ensure that all default credentials are changed to strong, unique passwords. Network segmentation should be implemented to isolate security systems from general network access, and regular security audits should be conducted to identify similar hardcoded credentials in other components. Additionally, system administrators should implement proper monitoring and logging mechanisms to detect unauthorized access attempts and maintain up-to-date vulnerability assessments to prevent similar issues in future deployments. The remediation process must include thorough testing to ensure that legitimate administrative functions remain operational while eliminating the security risk posed by the hardcoded credentials.