CVE-2018-21234 in Jodd
Summary
by MITRE
Jodd before 5.0.4 performs Deserialization of Untrusted JSON Data when setClassMetadataName is set.
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Analysis
by VulDB Data Team • 05/22/2020
The vulnerability identified as CVE-2018-21234 affects the Jodd framework version prior to 5.0.4, specifically when the setClassMetadataName configuration is enabled. This represents a critical security flaw that enables remote code execution through improper input validation during JSON deserialization processes. The issue arises from the framework's handling of untrusted JSON data when class metadata is explicitly set, creating an attack surface that can be exploited by malicious actors to execute arbitrary code on affected systems.
The technical root cause of this vulnerability stems from the framework's deserialization mechanism failing to properly validate or sanitize JSON input when class metadata is present. When setClassMetadataName is configured, Jodd attempts to map JSON data to specific Java classes, but does not adequately verify the integrity or authenticity of the class information contained within the JSON payload. This weakness allows attackers to inject malicious class information that can trigger the execution of unintended code during the deserialization process. The vulnerability aligns with CWE-502 which specifically addresses Deserialization of Untrusted Data, a well-documented weakness that frequently leads to remote code execution in Java applications.
The operational impact of this vulnerability is severe and far-reaching across organizations using affected versions of the Jodd framework. Attackers can exploit this flaw remotely without requiring authentication, potentially gaining full control over affected systems. The vulnerability affects web applications, microservices, and any system that relies on Jodd's JSON processing capabilities with class metadata configuration enabled. Successful exploitation can result in data breaches, system compromise, and complete loss of application integrity, making this a critical concern for enterprise security teams. The attack vector typically involves sending specially crafted JSON payloads containing malicious class references that bypass normal security controls during the deserialization phase.
Organizations should immediately upgrade to Jodd version 5.0.4 or later to remediate this vulnerability, as no effective workarounds exist for the affected versions. Security teams should conduct comprehensive vulnerability assessments to identify all systems utilizing vulnerable Jodd configurations, particularly those with setClassMetadataName enabled. The mitigation strategy should include implementing strict input validation, disabling unnecessary deserialization features, and monitoring for suspicious JSON data patterns. Additionally, organizations should consider implementing application firewalls and runtime protection mechanisms to detect and block malicious deserialization attempts. This vulnerability demonstrates the critical importance of proper input validation and secure deserialization practices, aligning with ATT&CK technique T1210 for exploiting weaknesses in remote services and T1059 for command and script injection. Organizations must also review their entire application stack to ensure no other components are vulnerable to similar deserialization attacks, as this represents a common pattern in Java application security vulnerabilities that frequently appears in security assessments and penetration testing reports.