CVE-2017-2651 in jenkins-mailer-plugin
Summary
by MITRE
jenkins-mailer-plugin before version 1.20 is vulnerable to an information disclosure while using the feature to send emails to a dynamically created list of users based on the changelogs. 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 • 04/27/2023
The vulnerability identified as CVE-2017-2651 affects the jenkins-mailer-plugin version 1.20 and earlier, presenting a significant information disclosure risk within Jenkins continuous integration environments. This flaw specifically impacts the plugin's functionality for sending emails to dynamically generated user lists based on changelog information from software builds. The security issue stems from an insufficient validation mechanism that allows for improper user identification and email address resolution during automated notification processes.
The technical implementation of this vulnerability resides in the email address mapping algorithm used by the mailer plugin when processing changelog information. The flaw operates by leveraging the local-part component of email addresses, which represents the portion of an email address before the @ symbol. This approach creates a dangerous mapping relationship where the system attempts to identify Jenkins users based on email local-parts rather than proper user account validation. When changelogs are processed, the system performs a lookup using the local-part of email addresses, potentially matching against users who have no actual Jenkins account or whose account access has been revoked.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass potential unauthorized communication channels within Jenkins environments. Attackers can exploit this weakness to send automated notifications to email addresses that do not correspond to legitimate Jenkins users, effectively creating a vector for spamming or phishing activities. In rare but serious cases, the vulnerability allows messages to be delivered to individuals who have no involvement in the project being built, as the system's user mapping logic fails to properly validate recipient identities against actual Jenkins user accounts.
This vulnerability aligns with CWE-200, which describes information disclosure vulnerabilities, and represents a specific case of improper input validation. The issue also maps to ATT&CK technique T1190, which covers exploitation of remote services through automated tools, as the vulnerability enables automated email delivery to unintended recipients. Organizations using Jenkins with the affected mailer plugin face risks including potential information leakage about system users, unauthorized email traffic, and possible exploitation for social engineering attacks against non-Jenkins users who receive these improperly routed messages.
The recommended mitigation strategy involves upgrading the jenkins-mailer-plugin to version 1.20 or later, where the vulnerability has been addressed through improved user validation mechanisms. Organizations should also implement additional monitoring of email delivery patterns to detect anomalous behavior that might indicate exploitation attempts. Security teams should conduct thorough reviews of their Jenkins email notification configurations to ensure proper user account validation and implement network-level controls to limit email server access. Regular security assessments of Jenkins plugins and continuous monitoring of security advisories for the platform are essential to prevent similar vulnerabilities from affecting production environments.