CVE-2015-7609 in Zimbra Mail Client
Summary
by MITRE
Synacor Zimbra Mail Client 8.6 before 8.6.0 Patch 5 has XSS via the error/warning dialog and email body content in Zimbra.
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Analysis
by VulDB Data Team • 06/17/2020
The vulnerability identified as CVE-2015-7609 affects the Synacor Zimbra Mail Client version 8.6 before patch 5, representing a significant cross-site scripting weakness that could compromise user security and system integrity. This vulnerability specifically targets the error/warning dialog functionality and email body content processing mechanisms within the Zimbra client interface, creating potential attack vectors that could be exploited by malicious actors to execute unauthorized code in the context of a victim's browser session.
The technical flaw stems from inadequate input validation and output encoding within the Zimbra client's rendering engine for error messages and email content. When users interact with the application, particularly when viewing error dialogs or processing email messages containing maliciously crafted payloads, the system fails to properly sanitize user-supplied data before displaying it to end users. This insufficient sanitization allows attackers to inject malicious scripts that execute within the victim's browser context, bypassing standard security mechanisms such as the same-origin policy that typically protects web applications from cross-site scripting attacks.
The operational impact of this vulnerability extends beyond simple script execution, as it creates opportunities for more sophisticated attacks including session hijacking, credential theft, and data exfiltration. An attacker could craft malicious emails or manipulate error conditions to inject JavaScript code that captures user credentials, steals session tokens, or redirects users to malicious websites. The vulnerability affects the core communication and error handling components of the Zimbra client, making it particularly dangerous as it can be triggered through normal email operations and error reporting mechanisms. This creates a persistent threat vector that remains active as long as the vulnerable version remains in use, potentially affecting thousands of users within an organization.
Organizations utilizing vulnerable Zimbra installations face significant risk of unauthorized access and data breaches, as the vulnerability can be exploited through simple email-based attacks without requiring special privileges or complex exploitation techniques. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and maps to ATT&CK technique T1566.001 for credential access through spearphishing attachments and T1059.001 for command and scripting interpreter usage. The remediation strategy involves applying the official patch 5 release from Synacor, which implements proper input sanitization and output encoding mechanisms to prevent malicious script execution. Organizations should also consider implementing additional security controls such as content security policies, web application firewalls, and user education programs to reduce the risk of exploitation while awaiting patch deployment.