CVE-2019-9670: Critical Vulnerability in Synacor Zimbra Collaboration Suite

The CVE-2019-9670 vulnerability affects the mailboxd component in Synacor Zimbra Collaboration Suite versions 8.7.x prior to 8.7.11p10. This vulnerability allows for XML External Entity injection (XXE), which can lead to unauthorized access to sensitive data, service disruption, and other critical impacts.

With a CVSS score of 9.8, this vulnerability is classified as critical. It poses severe risks to confidentiality, integrity, and availability, making it imperative for organizations using affected versions to act swiftly.

Risk to organizations includes potential exposure of sensitive information and unauthorized system access, which underscores the urgency of addressing this vulnerability.

Known exploits exist for this vulnerability, indicating that it may be actively targeted by attackers. Consequently, organizations should prioritize patching immediately.

Vulnerability Details

The vulnerability arises from improper handling of XML external entity references in the mailboxd component, as evidenced by the Autodiscover.xml file. The CVSS 3.1 score reflects a network attack vector with low complexity and no required privileges or user interaction.

Affected products include the Synacor Zimbra Collaboration Suite versions 8.7.0 to 8.7.11p9, as well as specific patches (8.7.11.p1 to p9). The CWE classification for this vulnerability is CWE-611.

Technical Analysis

The root cause of this vulnerability is the insufficient validation of XML input, allowing attackers to inject malicious entities. The attack vector is network-based with low complexity, requiring no privileges or user interaction. This vulnerability has significant confidentiality, integrity, and availability impacts.

Organizations using affected versions should assess their exposure and consider immediate remediation to mitigate the risk of exploitation.

Risk & Impact Analysis

The real-world deployment risk associated with CVE-2019-9670 is high due to the potential blast radius of an exploit. Attackers may leverage this vulnerability to access sensitive data, leading to unauthorized disclosure and potential financial impacts.

Given the vulnerability's critical CVSS score and active exploitation status, organizations must treat this with utmost urgency. Immediate patching should be prioritized to safeguard against potential breaches.

Exploitation Status

Affected Versions

Affected versions include all Synacor Zimbra Collaboration Suite versions from 8.7.0 to 8.7.11p9, including patches 8.7.11.p1 through 8.7.11.p9. Organizations should ensure they are using a secure version.

Mitigation & Remediation

To mitigate this vulnerability, organizations should apply the latest updates from Synacor as soon as possible. For those unable to apply patches immediately, consider implementing network segmentation and monitoring solutions to limit exposure.

For guidance on security assessments, organizations may refer to the application security assessment services provided by AppSecure.

Detection Guidance

Monitoring for unusual patterns in logs, such as unexpected XML processing or attempts to access internal services, can help detect potential exploitation of this vulnerability. Ensure that system integrity checks are in place.

AppSecure Threat Intelligence Insight

CVE-2019-9670 is a significant example of the risks associated with improper XML handling. Security teams should take this as a reminder of the importance of secure coding practices, particularly when dealing with external entities in XML.

For further reading on securing applications and preventing vulnerabilities, organizations are encouraged to explore the penetration testing methodology and the vulnerability management program design best practices provided by AppSecure.

Additionally, reviewing the web application penetration testing approach can provide insights into identifying and mitigating similar vulnerabilities.