CVE-2021-21698 in Subversion Plugin
Summary
by MITRE • 11/04/2021
Jenkins Subversion Plugin 2.15.0 and earlier does not restrict the name of a file when looking up a subversion key file on the controller from an agent.
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Analysis
by VulDB Data Team • 11/09/2021
The vulnerability identified as CVE-2021-21698 affects the Jenkins Subversion Plugin version 2.15.0 and earlier, presenting a critical security flaw that stems from insufficient input validation during the handling of subversion key files. This issue occurs when the plugin processes file names during the lookup of subversion key files on the Jenkins controller from remote agents, creating an opportunity for path traversal attacks. The flaw allows unauthorized access to sensitive files on the controller system by manipulating the file name parameter used in the key file lookup process, potentially enabling attackers to access arbitrary files that should remain protected within the Jenkins environment.
The technical implementation of this vulnerability resides in the plugin's failure to properly sanitize or validate the file name parameter when retrieving subversion key files from the controller's file system. This weakness creates a path traversal condition where an attacker can manipulate the file path to navigate beyond the intended directory boundaries and access files outside of the designated key file locations. The vulnerability is particularly concerning because it operates at the controller level, where sensitive configuration data, authentication credentials, and potentially other critical system files may be accessible through this flaw. The issue directly relates to CWE-22 Path Traversal and CWE-73 Path Traversal, as it enables attackers to manipulate file paths and access unauthorized resources within the Jenkins environment. From an operational perspective, this vulnerability represents a significant risk to organizations relying on Jenkins for continuous integration and deployment workflows, as it could allow attackers to extract sensitive information, compromise build processes, or potentially escalate privileges within the Jenkins infrastructure.
The impact of CVE-2021-21698 extends beyond simple information disclosure, as it can be leveraged as a stepping stone for more sophisticated attacks within the Jenkins ecosystem. Attackers could potentially access not only subversion key files but also other sensitive artifacts stored on the controller, including build scripts, configuration files containing secrets, or other system-level information. This vulnerability aligns with ATT&CK technique T1213 Data from Information Repositories, as it enables unauthorized access to repository data within the Jenkins environment. The flaw is particularly dangerous in environments where Jenkins controls access to version control systems and where sensitive build artifacts or deployment configurations are stored. Organizations using Jenkins with the affected Subversion plugin version face significant risk of credential theft, unauthorized code access, and potential compromise of their entire CI/CD pipeline security posture. The vulnerability demonstrates a critical gap in Jenkins plugin security practices and highlights the importance of proper input validation and file system access controls in distributed build environments where agents interact with central controllers.
Organizations should immediately update their Jenkins Subversion Plugin to version 2.16.0 or later, which contains the necessary patches to address this vulnerability. The mitigation strategy involves not only applying the software update but also implementing additional security controls such as restricting agent-to-controller communication, implementing proper file access controls, and conducting comprehensive security reviews of all Jenkins plugins in use. System administrators should also consider implementing network segmentation to limit access to Jenkins controllers and regularly audit file permissions for sensitive directories. Additionally, organizations should monitor their Jenkins environments for suspicious file access patterns and implement intrusion detection systems that can identify potential path traversal attempts. The vulnerability serves as a reminder of the critical importance of keeping CI/CD infrastructure components updated and maintaining robust security practices throughout the software development lifecycle, particularly when dealing with plugins that interact with file systems and external repositories.