CVE-2017-2654 in jenkins-email-ext
Summary
by MITRE
jenkins-email-ext before version 2.57.1 is vulnerable to an Information Exposure. The Email Extension Plugins is able to send emails to a dynamically created list of users based on the changelogs, like authors of SCM changes since the last successful build. This could in some cases result in emails being sent to people who have no user account in Jenkins, and in rare cases even people who were not involved in whatever project was being built, due to some mapping based on the local-part of email addresses.
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Analysis
by VulDB Data Team • 05/01/2023
The vulnerability identified as CVE-2017-2654 affects the Jenkins Email Extension Plugin version 2.57.1 and earlier, presenting an information exposure risk that stems from improper user identification and email address mapping mechanisms. This flaw operates within the plugin's functionality designed to send notifications to users based on source code management changes, creating an unexpected pathway for unintended recipients to receive sensitive communications. The vulnerability specifically manifests when the plugin attempts to map email addresses to Jenkins user accounts using the local-part of email addresses, which represents the portion of an email address preceding the @ symbol.
The technical implementation of this vulnerability involves the plugin's user resolution process that relies on email address local-part matching rather than robust user account verification. When SCM changelogs trigger email notifications, the system attempts to identify recipients by matching the local-part of email addresses against existing Jenkins user accounts. This approach creates a fundamental security gap because it allows arbitrary email addresses to be resolved to non-existent Jenkins accounts, leading to information exposure through unintended recipients. The mapping process operates without proper validation that ensures the email address corresponds to an actual Jenkins user account, enabling attackers to exploit this mechanism to discover valid email addresses or gain insights into the system's user base.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can result in sensitive project information being transmitted to individuals who should not have access to such communications. Attackers could potentially exploit this flaw to map valid email addresses within the organization's Jenkins environment, creating a reconnaissance pathway for further attacks. The vulnerability particularly affects scenarios where the plugin sends notifications to authors of SCM changes, as it may inadvertently include individuals who have no formal user accounts in Jenkins but whose email addresses match the local-part resolution logic. This exposure represents a violation of the principle of least privilege and can lead to unauthorized information dissemination.
Organizations implementing the affected Jenkins Email Extension Plugin should immediately upgrade to version 2.57.1 or later to remediate this vulnerability. The patch addresses the information exposure issue by implementing proper user account validation before sending email notifications, ensuring that only legitimate Jenkins users receive communications. Security teams should also conduct thorough reviews of their email notification configurations to identify any potential misuse of the plugin's dynamic recipient resolution features. Additionally, implementing network segmentation and access controls around Jenkins instances can help limit the potential impact of information exposure through this vulnerability. This remediation aligns with security best practices outlined in the CWE-200 standard for information exposure and supports defensive strategies recommended in the MITRE ATT&CK framework for credential access and reconnaissance activities. The vulnerability demonstrates the importance of proper input validation and user account verification in security-critical components, particularly those handling sensitive communications within enterprise environments.