CVE-2020-2113 in Git Parameter Plugin
Summary
by MITRE
Jenkins Git Parameter Plugin 0.9.11 and earlier does not escape the default value shown on the UI, resulting in a stored cross-site scripting vulnerability exploitable by users with Job/Configure permission.
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Analysis
by VulDB Data Team • 02/13/2020
The vulnerability identified as CVE-2020-2113 affects the Jenkins Git Parameter Plugin version 0.9.11 and earlier, representing a critical security flaw that undermines the integrity of Jenkins continuous integration environments. This issue stems from inadequate input validation and output sanitization within the plugin's user interface components, specifically when handling default values for Git parameters. The vulnerability creates a persistent cross-site scripting attack vector that can be exploited by malicious actors with relatively limited permissions, making it particularly dangerous in shared or collaborative development environments where multiple users have access to job configuration functionalities.
The technical flaw manifests when the plugin fails to properly escape special characters in default parameter values displayed within the Jenkins web interface. This omission allows attackers to inject malicious JavaScript code into parameter fields, which then executes in the context of other users who view the affected configuration pages. The vulnerability is classified as a stored XSS attack because the malicious payload is permanently stored within the Jenkins configuration and persists until manually removed, making it particularly insidious as it can affect any user who accesses the vulnerable job configuration page. The attack requires only the Job/Configure permission level, which is commonly granted to developers and team members who need to modify build parameters, significantly expanding the potential attack surface.
From an operational impact perspective, this vulnerability exposes Jenkins environments to several serious risks including unauthorized data exfiltration, session hijacking, and privilege escalation attacks. An attacker could potentially steal sensitive information such as API keys, credentials, or source code repository access tokens that might be stored within the Git parameters. The stored nature of the vulnerability means that even users who do not actively interact with the compromised parameters could be affected, as the malicious script executes automatically when the configuration page loads. This creates a persistent threat that can remain undetected for extended periods, potentially allowing attackers to establish long-term access to the Jenkins environment and associated systems.
Organizations should immediately implement mitigations including updating to Jenkins Git Parameter Plugin version 0.9.12 or later, which contains the necessary fixes to properly escape user-supplied values in the UI. Additionally, administrators should conduct comprehensive audits of existing Jenkins configurations to identify and remediate any instances where default parameter values might contain unescaped special characters. Network segmentation and access controls should be reviewed to limit the scope of potential exploitation, while monitoring systems should be enhanced to detect unusual configuration changes or attempts to inject malicious content into Jenkins jobs. The vulnerability aligns with CWE-79 (Cross-site Scripting) and can be mapped to ATT&CK technique T1059.007 (Command and Scripting Interpreter: JavaScript) within the adversary tactics and techniques framework, emphasizing the need for robust input validation and output encoding practices throughout the Jenkins ecosystem.