CVE-2020-2109: 
Java vulnerability analysis and mitigation

CVE-2020-2109 is a high-severity vulnerability discovered in Jenkins Pipeline: Groovy Plugin versions 2.78 and earlier. The vulnerability was disclosed on February 12, 2020, affecting the sandbox protection mechanism in the plugin. The issue was identified by Nils Emmerich of ERNW Research GmbH and tracked as SECURITY-1710 (Jenkins Advisory).

The vulnerability allows circumvention of sandbox protection through default parameter expressions in CPS-transformed methods. This security flaw exists in the workflow-cps component of the Jenkins Pipeline: Groovy Plugin. The vulnerability has been assigned a severity rating of High according to the CVSS scoring system (Jenkins Advisory).

When exploited, this vulnerability allows attackers with the ability to specify and run sandboxed Pipelines to execute arbitrary code in the context of the Jenkins controller JVM. This represents a significant security risk as it enables unauthorized code execution with Jenkins controller privileges (Jenkins Advisory).

The vulnerability was patched in Pipeline: Groovy Plugin version 2.79, which implements proper sandbox protection for default parameter expressions. Users are strongly advised to upgrade to this version or later to address the security risk. The fix ensures that these expressions are properly subject to sandbox protection (Jenkins Advisory).