CVE-2020-2167 in OpenShift Pipeline Plugin
Summary
by MITRE
Jenkins OpenShift Pipeline Plugin 1.0.56 and earlier does not configure its YAML parser to prevent the instantiation of arbitrary types, resulting in a remote code execution vulnerability.
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Analysis
by VulDB Data Team • 03/26/2020
The vulnerability identified as CVE-2020-2167 affects the Jenkins OpenShift Pipeline Plugin version 1.0.56 and earlier, presenting a critical remote code execution risk through improper YAML parsing configuration. This flaw resides in how the plugin handles YAML input during pipeline execution, creating a pathway for malicious actors to execute arbitrary code on the Jenkins server. The issue stems from the plugin's failure to restrict type instantiation during YAML deserialization, allowing attackers to craft specially crafted YAML payloads that can trigger unintended object creation and execution within the Jenkins environment.
The technical root cause of this vulnerability aligns with CWE-502, which specifically addresses deserialization of untrusted data, and represents a classic example of insecure deserialization where YAML parsers are configured without proper type restrictions. When Jenkins processes pipeline definitions containing crafted YAML content, the parser attempts to instantiate arbitrary Java classes specified within the YAML structure, bypassing normal security boundaries. This behavior enables attackers to leverage the YAML parser to execute malicious code with the privileges of the Jenkins process, potentially leading to complete system compromise. The vulnerability exists because the plugin does not implement safe YAML parsing practices that would prevent instantiation of dangerous classes or restrict the parser to a predefined whitelist of allowed types.
The operational impact of CVE-2020-2167 extends beyond simple remote code execution, as it represents a severe privilege escalation vector within CI/CD environments where Jenkins typically runs with elevated permissions. Attackers can leverage this vulnerability to gain full control over the build server, potentially accessing source code repositories, stealing credentials, or using the compromised system as a launch point for further attacks within the network infrastructure. The vulnerability is particularly dangerous in enterprise environments where Jenkins serves as a central automation hub, as compromise of a single Jenkins instance can expose multiple projects and applications under its control. Additionally, the attack surface is broadened by the fact that Jenkins plugins often have access to sensitive system resources and can interact with various external services through pipeline definitions.
Mitigation strategies for CVE-2020-2167 primarily focus on immediate patching of the affected Jenkins OpenShift Pipeline Plugin to version 1.0.57 or later, which includes proper YAML parser configuration that restricts type instantiation. Organizations should implement network segmentation to limit access to Jenkins servers, enforce strict access controls and authentication mechanisms, and regularly audit pipeline definitions for suspicious content. The remediation process should include comprehensive vulnerability scanning to identify any instances of the vulnerable plugin version and thorough testing of patched environments to ensure no regression in functionality. Security teams should also consider implementing runtime monitoring and anomaly detection for unusual Jenkins activity, as well as establishing secure coding practices for pipeline definitions that prevent untrusted input from being processed without proper sanitization. This vulnerability demonstrates the importance of proper input validation and secure deserialization practices, aligning with ATT&CK technique T1059.001 for command and scripting interpreter execution through compromised automation systems.