CVE-2020-7796: A Detailed Guide to the Zimbra Collaboration Suite Vulnerability
After upgrading, use the zmcontrol -v command to ensure the correct version is active.
Zimbra (Synacor) acted quickly to address this issue, releasing patches in late 2020. To secure a Zimbra Collaboration Suite instance against CVE-2020-7796, administrators must take the following steps: cve20207796 zimbra collaboration suite full
CVE-2020-7796 is a vulnerability in the Zimbra Collaboration Suite that allows an attacker to access sensitive information, including authentication tokens and user credentials. The vulnerability is caused by a lack of proper validation and sanitization of user input, which enables an attacker to inject malicious code and execute unauthorized actions.
The ProxyServlet blindly follows the target parameter, ignoring host restrictions. It returns the login page of the Admin Console. CVE-2020-7796: A Detailed Guide to the Zimbra Collaboration
High (CVSS Score: 7.5 - 8.8 depending on the environment)
If immediate patching is not possible, security teams should implement the following Acunetix-recommended controls : The vulnerability is caused by a lack of
structure for testing your own environment against this SSRF? CVE-2020-7796 Detail - NVD
CVE-2020-7796 serves as a stark reminder of the risks associated with complex enterprise collaboration suites. The combination of an unrestricted upload feature and improper access controls created a "full" compromise scenario for thousands of mail servers. For organizations using Zimbra, continuous patching and rigorous monitoring of web directories remain the most effective defenses against such vulnerabilities.
An attacker uploads a file titled alert(document.cookie) .txt .
[Attacker] │ ├── (1) Sends crafted HTTP Request targeting Zimlet JSP URL │ with a malicious target parameter (e.g., http://169.254.169...) ▼ [Zimbra Mail Server (Vulnerable)] │ ├── (2) Fails to validate target parameter ├── (3) Executes backend HTTP request on behalf of the attacker ▼ [Internal Network / Cloud Metadata Engine]