CVE-2020-10199 in Nexus Repository
Summary
by MITRE
Sonatype Nexus Repository before 3.21.2 allows JavaEL Injection (issue 1 of 2).
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Analysis
by VulDB Data Team • 02/05/2025
The vulnerability CVE-2020-10199 represents a critical Java Expression Language injection flaw discovered in Sonatype Nexus Repository software versions prior to 3.21.2. This vulnerability falls under the category of server-side template injection attacks where malicious input can be executed within the Java Expression Language environment. The flaw specifically affects the repository management system's handling of user-supplied data during template processing, creating an avenue for remote code execution and arbitrary command execution on the affected system. The vulnerability is classified as a CWE-94 weakness, specifically related to improper control of generation of code, which allows attackers to inject and execute malicious expressions through crafted input parameters.
The technical exploitation of this vulnerability occurs when the Nexus Repository server processes user-provided data within Java Expression Language contexts without proper sanitization or validation. Attackers can craft malicious payloads that, when processed by the repository's template engine, execute arbitrary Java code on the server with the privileges of the Nexus service account. This injection typically occurs through parameters that are directly passed to the Expression Language evaluator without appropriate input filtering or escaping mechanisms. The vulnerability is particularly dangerous because it can be exploited remotely without authentication, allowing attackers to gain full control over the repository server and potentially access sensitive artifacts, credentials, and configuration data stored within the repository.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and data exfiltration capabilities. Organizations using affected versions of Nexus Repository face significant risks including unauthorized access to proprietary software artifacts, potential credential theft from repository configurations, and the ability to modify or delete repository content. The vulnerability also enables attackers to establish persistence mechanisms within the repository environment, making detection and remediation more challenging. Security teams must consider the potential for lateral movement within network environments where Nexus repositories are used as central artifact repositories, as compromised systems can serve as launching points for broader attacks.
Mitigation strategies for CVE-2020-10199 focus primarily on immediate version upgrades to Nexus Repository 3.21.2 or later, which contain the necessary patches to prevent Java Expression Language injection. Organizations should also implement network segmentation and access controls to limit exposure of Nexus repositories to untrusted networks. Additional defensive measures include monitoring for suspicious template processing activities, implementing web application firewalls to detect and block malicious payload patterns, and conducting thorough security assessments of repository configurations. The vulnerability demonstrates the importance of proper input validation and sanitization in web applications, aligning with ATT&CK technique T1059.007 for command and script injection. Security administrators should also consider implementing automated patch management processes to ensure timely deployment of security updates and maintain comprehensive audit logs to detect potential exploitation attempts.