CVE-2020-2306 in Mercurial Plugin
Summary
by MITRE • 11/04/2020
A missing permission check in Jenkins Mercurial Plugin 2.11 and earlier allows attackers with Overall/Read permission to obtain a list of names of configured Mercurial installations.
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Analysis
by VulDB Data Team • 12/02/2020
The vulnerability identified as CVE-2020-2306 represents a critical authorization bypass issue within the Jenkins Mercurial Plugin ecosystem. This flaw exists in versions 2.11 and earlier, where the plugin fails to properly validate user permissions before exposing sensitive configuration information. The vulnerability specifically affects systems where Jenkins serves as a continuous integration and delivery platform, with the Mercurial plugin enabling integration with mercurial version control systems. Attackers exploiting this weakness can leverage their existing Overall/Read permission to gain unauthorized access to information about configured mercurial installations, including installation names and potentially other related configuration details.
The technical implementation of this vulnerability stems from a missing permission check within the plugin's codebase, which violates fundamental security principles of least privilege and access control. According to CWE-284, this represents an improper access control scenario where the system fails to properly enforce authorization checks before allowing access to sensitive resources. The flaw operates at the application level where the plugin does not adequately verify whether authenticated users possess the appropriate privileges to view mercurial installation configurations. This missing validation occurs during the information disclosure phase, where the system should enforce stricter permission boundaries before returning any configuration data to requesting users.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with reconnaissance data that can be leveraged for further exploitation attempts. An attacker with Overall/Read permission can enumerate mercurial installations and potentially discover system architecture details that may reveal other vulnerabilities or attack vectors. This information can be particularly valuable for attackers planning targeted attacks against specific mercurial configurations or those seeking to understand the broader system landscape. The vulnerability aligns with ATT&CK technique T1069.001 for credential access and reconnaissance activities, as it enables attackers to gather system information that could facilitate privilege escalation or lateral movement within the Jenkins environment.
Organizations utilizing Jenkins with Mercurial plugin versions 2.11 or earlier face significant risk exposure from this vulnerability, particularly in environments where multiple mercurial installations exist. The attack surface expands when considering that this information disclosure could reveal details about repository locations, authentication mechanisms, or integration points that may be exploited in subsequent attacks. Security teams should recognize that this vulnerability demonstrates poor input validation and access control implementation patterns that are commonly observed in legacy systems. The impact is compounded by the fact that many organizations may not immediately detect this information disclosure due to its passive nature, allowing attackers to gather intelligence over extended periods without triggering immediate alerts.
Mitigation strategies should focus on immediate plugin version updates to 2.12 or later, which contain the necessary permission check fixes. Organizations should also implement additional monitoring for unusual access patterns to configuration information and consider restricting Overall/Read permissions to only essential personnel. The remediation process should include comprehensive security reviews of all Jenkins plugins to identify similar permission bypass vulnerabilities. System administrators should ensure that proper access control policies are implemented at both the Jenkins level and underlying infrastructure, adhering to principle of least privilege and separation of duties. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar issues across the entire Jenkins ecosystem, ensuring that access controls function properly for all plugin components and system interfaces.