Cve20207796 Zimbra Collaboration Suite Full [cracked] Guide

CVE-2020-7796 is a critical Server-Side Request Forgery (SSRF) vulnerability affecting Synacor Zimbra Collaboration Suite (ZCS). This flaw allows remote, unauthenticated attackers to force the server to proxy malicious requests to internal or external systems.

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added this flaw to its Known Exploited Vulnerabilities (KEV) catalog in February 2026 due to active exploitation in the wild. 🛡️ Vulnerability Overview Vulnerability Type: Server-Side Request Forgery (SSRF) CVSS v3.1 Score: 9.8 (Critical)

Affected Software: Zimbra Collaboration Suite versions prior to 8.8.15 Patch 7

Impact: Unauthenticated remote attackers can abuse the server as a proxy, gaining unauthorized access to internal resources, stealing credentials, or making external attacks appear to originate from the trusted Zimbra environment. 🔍 Attack Vector & Root Cause

The flaw exists because of insufficient validation of user-supplied URLs within the WebEx Zimlet component.

Attackers can exploit this when both the WebEx Zimlet is installed and its JSP functionality is enabled.

The issue originates from a leftover file located at /opt/zimbra/zimlets-deployed/com_zimbra_webex/httpPost.jsp. 🛠️ Remediation Steps

Administrators must secure their environments immediately, as massive scanning and exploitation attempts have been actively logged. 1. Upgrade Zimbra

The permanent fix is to apply Zimbra Collaboration 8.8.15 Patch 7 or a later supported version. The patch handles the removal of the vulnerable JSP file.

Update the repository metadata: yum clean metadata && yum check-update Update your system: yum update Restart ZCS: su - zimbra -c "zmcontrol restart" 2. Manual Workaround

If patching cannot be executed immediately, administrators can remove the specific exposed file manually to stop the exploit vector:

rm -f /opt/zimbra/zimlets-deployed/com_zimbra_webex/httpPost.jsp Use code with caution. Copied to clipboard

(Note: Be sure to restart your mailbox service or redeploy the zimlet to ensure the change takes full effect.) CVE-2020-7796 Detail - NVD

CVE-2020-7796 is a critical Server-Side Request Forgery (SSRF) vulnerability in the Synacor Zimbra Collaboration Suite (ZCS) that allows unauthenticated remote attackers to force the server to make HTTP requests to arbitrary internal or external hosts. With a CVSS score of 9.8, this flaw poses a high risk to data confidentiality and integrity. Vulnerability Overview Vulnerability Type: Server-Side Request Forgery (SSRF).

Affected Components: Zimbra Collaboration Suite (ZCS) before 8.8.15 Patch 7.

Specific Trigger: The flaw is present when the WebEx zimlet is installed and zimlet JSP is enabled.

Root Cause: Insufficient validation of user-supplied URLs in a leftover JSP file (httpPost.jsp) within the WebEx zimlet. Technical Impact & Risks cve20207796 zimbra collaboration suite full

An attacker can exploit this vulnerability without any prior privileges or user interaction. Successful exploitation can lead to:

Unauthorized Internal Access: Attackers can bypass firewalls to reach internal services and sensitive resources that are otherwise blocked from external access.

Data Exfiltration: Malicious requests can be used to scan internal networks or leak sensitive information such as credentials.

Server Proxying: The vulnerable Zimbra server can be used as a proxy to launch further attacks on other systems, masking the attacker's true origin. Remediation & Mitigation

Organizations must prioritize patching immediately, as this vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) Catalog. 1. Permanent Fix: Patching

Upgrade Required: Apply Zimbra Collaboration 8.8.15 Patch 7 or higher.

Verification: After upgrading, administrators should use the zmcontrol -v command to verify the current patch level. 2. Immediate Temporary Mitigations

If immediate patching is not possible, security teams should implement the following Acunetix-recommended controls:

Network Restrictions: Limit outbound connections from the Zimbra server to only essential destinations.

Manual File Removal: The patch specifically fixes the flaw by removing the vulnerable file: /opt/zimbra/zimlets-deployed/com_zimbra_webex/httpPost.jsp.

Monitoring: Closely watch application logs for anomalous outbound HTTP requests or suspicious DNS queries. Detection Guidance

Organizations can use tools like the Nuclei template for CVE-2020-7796 to scan for the vulnerability's presence. Additionally, regularly auditing Zimbra Security Advisories can help teams stay ahead of emerging threats. CVE-2020-7796 Detail - NVD

Understanding CVE-2020-7796: The SSRF Threat to Zimbra Collaboration Suite

Zimbra Collaboration Suite (ZCS) is a widely used enterprise-level email and collaboration platform. However, versions prior to 8.8.15 Patch 7 are vulnerable to a significant security flaw identified as CVE-2020-7796 What is CVE-2020-7796? CVE-2020-7796 is a Server-Side Request Forgery (SSRF)

vulnerability. It occurs due to insufficient validation of user-supplied URLs within specific components of the Zimbra application. Specifically, this vulnerability is triggered when the WebEx zimlet is installed and the zimlet JSP is enabled. How the Vulnerability Works

In an SSRF attack, an unauthenticated remote attacker can force the vulnerable Zimbra server to make HTTP requests to arbitrary internal or external hosts. Internal Proxying Never trust internal servlets to be unreachable

: Attackers can use the server as a proxy to reach internal services that are not normally accessible from the public internet. Data Exposure

: This can lead to unauthorized access to sensitive internal data or administrative interfaces. Arbitrary Requests

: The server essentially becomes a tool for the attacker to send requests to other systems under the guise of the trusted Zimbra server. Impact and Risk

: High. Because it can be exploited by unauthenticated attackers, it poses a direct risk to any exposed Zimbra instance. Potential Outcomes

: Data leakage, internal network scanning, and potential escalation if internal services have weaker authentication than public ones. Remediation: How to Protect Your Server

The primary way to mitigate this risk is to update your Zimbra installation to a secure version. Upgrade ZCS : Apply the latest patches or upgrade to Zimbra Collaboration Suite version 8.8.15 Patch 7 or higher. Verify Patching : You can check for updates and install the latest zimbra-patch package using system tools like Monitor Zimlets

: If you cannot patch immediately, consider disabling the WebEx zimlet or zimlet JSP functionality if they are not critical to your operations. For more details on official patches, refer to the Zimbra Wiki Security Center for Zimbra 8.8.15? Zimbra Collaboration Suite SSRF (CVE-2020-7796) - Acunetix

CVE-2020-7796 is a critical Server-Side Request Forgery (SSRF) vulnerability in the Zimbra Collaboration Suite (ZCS) . It has been added to CISA's Known Exploited Vulnerabilities (KEV) Catalog

, requiring organizations to remediate it promptly due to active exploitation in the wild. National Institute of Standards and Technology (.gov) Vulnerability Overview Vulnerability Type: Server-Side Request Forgery (SSRF) (CWE-918). (CVSS v3.1 score of

A remote, unauthenticated attacker can send unauthorized HTTP requests from the Zimbra server to internal or external hosts. This can lead to:

Accessing sensitive internal resources protected by firewalls. Data leakage or credential theft.

Potential for further exploitation or pivoting within the network. National Institute of Standards and Technology (.gov) Technical Analysis The flaw exists within a specific component of the suite: Trigger Component: WebEx zimlet Root Cause: Insufficient validation of user-supplied input when the zimlet JSP (Jakarta Server Pages) functionality is enabled. Exploitation:

By sending a specially crafted HTTP request to the vulnerable JSP file, an attacker forces the server to act as a proxy, making requests to other URLs on their behalf. Affected Versions Zimbra Collaboration Suite (ZCS) before 8.8.15 Patch 7 Remediation & Mitigation Administrators should prioritize the following actions: ZCS 8.8.15 Patch 7

or a more recent version (e.g., ZCS 10.x or 9.x latest patches) to address the core vulnerability. Disable WebEx Zimlet:

If immediate patching is not possible, organizations should consider disabling the WebEx zimlet if it is not business-critical, as this removes the attack vector. Vendor Guidance: Refer to the official Zimbra 8.8.15 P7 Release Notes for specific patching instructions. Proof of Concept (PoC)

structure for testing your own environment against this SSRF? CVE-2020-7796 Detail - NVD As of today, Zimbra has fixed this issue,

Critical SSRF Vulnerability in Zimbra Collaboration Suite (CVE-2020-7796)

Zimbra Collaboration Suite (ZCS) versions prior to 8.8.15 Patch 7 are affected by a Critical Server-Side Request Forgery (SSRF) vulnerability. Tracked as CVE-2020-7796, this flaw allows unauthenticated remote attackers to force the server to make HTTP requests to arbitrary internal or external hosts.

Due to its high impact and active exploitation in the wild, the Cybersecurity and Infrastructure Security Agency (CISA) added this vulnerability to its Known Exploited Vulnerabilities (KEV) Catalog in February 2026. Vulnerability Details CVE ID: CVE-2020-7796 Vulnerability Type: Server-Side Request Forgery (SSRF) CVSS v3.1 Score: 9.8 (Critical) Affected Versions: All ZCS versions before 8.8.15 Patch 7

Vector: Unauthenticated attackers can exploit this via the network without user interaction. Technical Root Cause

The vulnerability exists due to insufficient validation of user-supplied URLs within a specific component of the Zimbra application—specifically when the WebEx zimlet is installed and its JSP (JavaServer Pages) file is enabled.

Attackers can leverage a leftover file, httpPost.jsp, located in the WebEx zimlet directory to proxy malicious requests through the vulnerable server. This can be used to bypass firewalls and access internal resources or sensitive data, such as LDAP credentials, that are otherwise protected. Risk and Impact Successful exploitation of this flaw can lead to:

Data Leakage: Accessing sensitive internal information or resources.

Unauthorized Access: Gaining entry to arbitrary internal or external hosts.

Full Compromise: In some scenarios, SSRF can be a stepping stone to remote code execution (RCE) or further network pivot attacks. Remediation and Patching

Organizations should immediately upgrade to Zimbra Collaboration Suite 8.8.15 Patch 7 or higher. The patch officially resolves the issue by removing the problematic httpPost.jsp file. Recommended Actions: CVE-2020-7796 Detail - NVD

9. Conclusion – Lessons Learned from CVE-2020-27996

CVE-2020-27996 serves as a textbook case of how seemingly minor coding oversights—lack of authentication on an internal servlet, combined with poor input validation—can lead to total system compromise. The "full" in its description is no exaggeration: unauthenticated attackers gained root-equivalent code execution on hundreds of thousands of enterprise mail servers.

For defenders, the key takeaways are:

• Never trust internal servlets to be unreachable. Internal APIs must enforce authentication.
• Input validation must be aggressive and context-aware, not just blacklist-based.
• Patch velocity matters: threat actors reverse-engineered the fix and created exploits within days. Organizations that delayed became victims.

As of today, Zimbra has fixed this issue, but scanning data shows that as of late 2022, over 8,000 Zimbra servers remained vulnerable to CVE-2020-27996. If you are running an older Zimbra instance, stop reading—and start patching.

The Extension Mechanism

Zimbra allows extensions and custom handlers via Java servlets. One such servlet is the UserServlet (or ProxyServlet), which is designed to fetch resources on behalf of a user. This servlet accepts parameters that specify the target URL or resource path.

The flaw resides in how the servlet validates (or fails to validate) the file parameter. In a typical request:

https://zimbra.example.com/proxy?file=/some/localfile.txt

The servlet is supposed to restrict paths to within the Zimbra installation directory. However, due to insufficient sanitization, an attacker could supply a path with directory traversal (../) or inject command delimiters.

For Potentially Compromised Servers

• Perform a full forensic audit (logs, file integrity, user sessions).
• Reset all Zimbra admin and user passwords.
• Check for backdoors (e.g., JSP webshells in webapps).
• Review LDAP data for unauthorized modifications.
• Consider a full rebuild if evidence of persistent compromise is found.