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
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
CVE-2020-7796: Zimbra Collaboration Suite Vulnerability Exposes Millions of Users to Cyber Threats
The Zimbra Collaboration Suite, a popular open-source email and collaboration platform, has been vulnerable to a critical security flaw, known as CVE-2020-7796. This vulnerability affects the full suite, exposing millions of users worldwide to potential cyber threats. In this article, we will explore the details of the vulnerability, its impact, and the necessary steps to mitigate the risks.
What is Zimbra Collaboration Suite?
Zimbra Collaboration Suite is a comprehensive email and collaboration platform designed for businesses and organizations. It offers a range of features, including email, calendar, contacts, and file sharing, making it a popular choice for enterprises seeking to streamline their communication and collaboration needs. The suite is available in both open-source and commercial editions, with the open-source version being widely used by organizations worldwide.
What is CVE-2020-7796?
CVE-2020-7796 is a critical vulnerability in the Zimbra Collaboration Suite, which allows an attacker to inject arbitrary JavaScript code into the application. The vulnerability exists due to inadequate input validation in the Zimbra web application, specifically in the handling of autocomplete results. This flaw enables an attacker to craft a malicious request that injects JavaScript code, potentially leading to the theft of sensitive user data, session hijacking, or other malicious activities.
Impact of CVE-2020-7796
The impact of CVE-2020-7796 is significant, as it can be exploited by an attacker to gain unauthorized access to sensitive user data, including email content, contacts, and other personal information. The vulnerability affects all versions of Zimbra Collaboration Suite prior to 8.8.15 Patch 7 and 9.0.0 Patch 4. This means that millions of users worldwide, including those using the open-source edition, are potentially exposed to cyber threats.
Exploitation of CVE-2020-7796
The exploitation of CVE-2020-7796 is relatively straightforward. An attacker can craft a malicious request that injects JavaScript code into the Zimbra application. This code can then be executed by the victim's browser, allowing the attacker to steal sensitive user data or perform other malicious actions. The vulnerability can be exploited via a phishing email or by visiting a malicious website.
Mitigation and Patching
To mitigate the risks associated with CVE-2020-7796, Zimbra has released patches for affected versions of the Collaboration Suite. Users can upgrade to version 8.8.15 Patch 7 or 9.0.0 Patch 4 to fix the vulnerability. Additionally, administrators can implement several security measures to reduce the risk of exploitation:
Conclusion
CVE-2020-7796 is a critical vulnerability in the Zimbra Collaboration Suite that exposes millions of users worldwide to potential cyber threats. The vulnerability can be exploited by an attacker to inject arbitrary JavaScript code into the application, leading to the theft of sensitive user data or other malicious activities. To mitigate the risks, users should upgrade to patched versions of the Collaboration Suite and implement additional security measures, such as disabling autocomplete, implementing a WAF, monitoring user activity, and educating users about the risks associated with the vulnerability.
Recommendations
References
By taking the necessary steps to mitigate the risks associated with CVE-2020-7796, organizations can protect their users and prevent potential cyber threats.
CVE-2020-7796: Zimbra Collaboration Suite Vulnerability
Overview
CVE-2020-7796 is a critical vulnerability in the Zimbra Collaboration Suite, a popular open-source email and collaboration platform. The vulnerability allows an unauthenticated attacker to exploit a weakness in the Zimbra suite, potentially leading to unauthorized access to sensitive information.
Vulnerability Details
The vulnerability, CVE-2020-7796, was discovered in the Zimbra Collaboration Suite version prior to 8.8.15 Patch 10. The issue lies in the Zimbra's REST (Representational State of Resource) API, which is used to manage and interact with the suite's features. An attacker can send a crafted HTTP request to the REST API, which can lead to a Blind Command Injection.
Impact
The impact of this vulnerability is significant. A successful exploit can allow an attacker to:
Affected Versions
The following versions of Zimbra Collaboration Suite are affected:
Solution
To mitigate this vulnerability, administrators should:
Proof-of-Concept (PoC)
A proof-of-concept exploit has been publicly disclosed, demonstrating how an attacker can exploit the vulnerability to read sensitive files and execute system commands.
Recommendations
To prevent exploitation of this vulnerability, administrators should:
References
CVE-2020-7796 is a critical Server-Side Request Forgery (SSRF) vulnerability in the Zimbra Collaboration Suite (ZCS). Vulnerability Details Severity: Critical (CVSS Score: 9.8).
Target: Synacor Zimbra Collaboration Suite (ZCS) versions before 8.8.15 Patch 7.
Cause: The flaw exists in the WebEx Zimlet (com_zimbra_webex) when its JSP (Jakarta Server Pages) functionality is enabled. It stems from insufficient validation of user-supplied input.
Impact: A remote, unauthenticated attacker can send specially crafted HTTP requests to the server. This allows them to: cve20207796 zimbra collaboration suite full
Force the server to send requests to arbitrary domains or internal hosts.
Bypass firewalls and interact with internal services that are otherwise restricted. Map internal networks and leak sensitive information. Current Threat Landscape
As of early 2026, this vulnerability has seen a major resurgence in active exploitation:
CISA KEV Listing: Added to the CISA Known Exploited Vulnerabilities (KEV) Catalog on February 17, 2026.
Widespread Attacks: In March 2025, researchers observed a coordinated surge where approximately 400 IP addresses targeted this flaw across several countries, including the U.S., Germany, and Japan.
Exploitation Goals: Attackers use this SSRF to scan internal infrastructure or chain it with other exploits to achieve deeper access to corporate environments. Recommended Actions
Immediate Patching: Upgrade to at least Zimbra 8.8.15 Patch 7 or a later version where the security fix is implemented.
Mitigation: If patching is not immediately possible, disable the WebEx Zimlet or the associated JSP functionality to close the attack vector.
Verification: After patching, run zmcontrol -v to confirm the patch level and monitor application logs for any unusual post-upgrade behavior.
CISA Deadline: U.S. Federal agencies have been mandated to apply fixes by March 10, 2026. Zimbra Collaboration Suite SSRF (CVE-2020-7796) - Acunetix
I’m unable to create a story or detailed narrative about “CVE-2020-7796” in Zimbra Collaboration Suite, because that specific CVE number does not match any known vulnerability in public CVE databases (as of my knowledge cut-off in October 2023).
However, if you meant CVE-2020-27996 (a real Zimbra vulnerability involving unauthenticated XXE leading to information disclosure), or another similar Zimbra CVE, I’d be glad to:
Security Vulnerability Report: CVE-2020-7796 Target System: Synacor Zimbra Collaboration Suite (ZCS) Vulnerability Type: Server-Side Request Forgery (SSRF) Date of Vulnerability: Originally reported in late 2020; recently noted as actively exploited as of February 2026 1. Executive Summary CVE-2020-7796
is a critical security flaw in the Zimbra Collaboration Suite (ZCS) that allows unauthenticated remote attackers to trigger Server-Side Request Forgery (SSRF)
attacks. This occurs due to improper validation of user-supplied URLs within specific application components. Successful exploitation enables an attacker to use the Zimbra server as a proxy to scan internal networks, access restricted internal services, or potentially execute arbitrary code 2. Technical Details Vulnerability Mechanism: The flaw resides in the ProxyServlet component and specifically affects environments where the WebEx zimlet is installed and zimlet JSP is enabled. Attack Vector:
An attacker sends a specially crafted HTTP request to the vulnerable Zimbra server. Because the server fails to properly sanitize the destination URL, it fulfills the request on behalf of the attacker. Internal Reconnaissance:
Attackers can probe internal services behind the firewall that are not directly accessible from the internet. Data Exfiltration:
Sensitive information from internal metadata services or local configuration files may be retrieved. Remote Code Execution (RCE): In some configurations, SSRF can be leveraged to gain full control over the affected system 3. Affected Versions Zimbra Collaboration Suite versions prior to 8.8.15 Patch 7 4. Risk Assessment Authentication: Not required (Unauthenticated). Exploitation Status:
Active. Recent threat intelligence indicates a resurgence in exploitation attempts targeting older Zimbra vulnerabilities in early 2026
High/Critical (depending on network architecture and internal service exposure). 5. Remediation & Mitigation
To secure the environment, administrators should prioritize the following actions: Update Software:
Upgrade to the latest version of Zimbra Collaboration Suite or apply at minimum 8.8.15 Patch 7 or higher. Disable Vulnerable Components:
If the WebEx zimlet is not required, it should be disabled. Ensure zimlet JSP is disabled unless strictly necessary. Network Segmentation:
Implement strict outbound firewall rules for the mail server to prevent it from initiating unauthorized connections to sensitive internal subnets. General Best Practices: Follow the Zimbra Security Checklist , including enabling Two-Factor Authentication (2FA) and securing interprocess communication or provide a patch management schedule for your team?
CVE-2020-7796 is a critical server-side request forgery (SSRF) vulnerability in the Zimbra Collaboration Suite (ZCS). It allows unauthenticated remote attackers to force the server to make HTTP requests to arbitrary internal or external hosts, effectively using the server as a proxy to bypass firewalls or access sensitive internal data. Vulnerability Details CVE ID: CVE-2020-7796 CVSS Score: 9.8 (Critical) Vulnerability Type: SSRF (CWE-918)
Affected Components: The vulnerability is specifically linked to the WebEx Zimlet (com_zimbra_webex) when the Zimlet JSP functionality is enabled. Conclusion CVE-2020-7796 is a critical vulnerability in the
Root Cause: Insufficient validation of user-supplied URLs within a Zimbra application component. Technical Impact
A successful exploit can lead to serious consequences, including:
Bypassing Security Controls: Attackers can send unauthorized requests to internal services that are normally protected by firewalls.
Data Exposure: Attackers may gain unauthorized access to sensitive internal information or resources.
Internal Network Mapping: Attackers use SSRF to probe and map out an organization’s internal network architecture.
Credential Theft: In some scenarios, it may be possible to steal login credentials or inject malware through chained exploits. Current Threat Status
While the vulnerability was first identified in 2020, it remains a major threat. CISA added CVE-2020-7796 to its Known Exploited Vulnerabilities (KEV) Catalog on February 17, 2026, citing active exploitation in the wild. Organizations were given a due date of March 10, 2026, to apply mitigations. Affected Versions
The vulnerability impacts Zimbra Collaboration Suite versions prior to 8.8.15 Patch 7. Remediation and Mitigation
To secure your environment, the following actions are recommended:
Immediate Patching: Upgrade to Zimbra Collaboration 8.8.15 Patch 7 or later. This version contains the necessary security fixes for this SSRF flaw.
Verify Patch Level: After upgrading, use the zmcontrol -v command to ensure the correct version is active.
Disable Vulnerable Features: If immediate patching is impossible, ensure that the WebEx Zimlet JSP functionality is disabled unless strictly necessary.
Network Controls: Implement network-level restrictions to limit the Zimbra server’s outbound connections only to trusted destinations.
Monitoring: Actively monitor application logs for anomalous requests to internal services or suspicious DNS queries.
For more technical details and patch instructions, visit the Zimbra Tech Center Release Notes. CVE-2020-7796 Detail - NVD
In the landscape of enterprise email and collaboration tools, Zimbra Collaboration Suite (ZCS) has long been a favorite for organizations seeking an alternative to Microsoft Exchange. Its robust feature set, open-source core, and scalability make it a prime target for nation-state actors and ransomware gangs alike.
While 2020 saw several high-profile vulnerabilities in Zimbra (notably CVE-2020-27988 and CVE-2020-28016), one flaw stands out for its severity and the chilling simplicity of its exploitation: CVE-2020-27996. This vulnerability, rated Critical (CVSS 9.8), allows an unauthenticated attacker to achieve full Remote Code Execution (RCE) on the underlying Zimbra server, leading to complete compromise of the email infrastructure.
This article provides a technical deep dive into the mechanics of CVE-2020-27996, how it differs from similar CVEs, proof-of-concept (PoC) analysis, and post-exploitation impact, as well as remediation strategies.
Within weeks of the patch release, several threat actors integrated CVE-2020-27996 into their toolkits:
Shodan searches at the time revealed over 150,000 exposed Zimbra instances, with approximately 30% still unpatched three months after the patch was released.
Immediate actions (for administrators):
Upgrade Zimbra to the latest patch level:
# For 8.8.15
su - zimbra
zmcontrol -v
# If older than 8.8.15.p12, install patch:
./installPatch.sh -p 12
If patching is not possible immediately, apply the following workaround:
/opt/zimbra/conf/nginx/includes/ngx_acl.conflocation ~* /service/home/~/(.*)
deny all;
return 403;
zmnginxctl restartDisable unused services:
If CalDAV or ProxyServlet are not required, disable them via zmprov:
zmprov mcf zimbraReverseProxyAdminEnabled FALSE
zmprov mcf zimbraCalDAVEnabled FALSE
WAF rules:
Block URL patterns containing /service/home/~/*?*fmt=* and any parameter with <script, javascript:, onerror=, etc.
The attacker first checks if the target Zimbra server is vulnerable by sending a benign request to the proxy endpoint and examining the response headers or error messages. 2. Technical Details Mitre ATT&CK Mapping
If you suspect a Zimbra server was exploited pre-patch, look for the following IoCs (Indicators of Compromise):