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HighCISA KEVExploited in the wildPublic exploit

SSRF in Zimbra Collaboration Suite ProxyServlet

IdentifiersCVE-2019-9621CWE-918· Server-Side Request Forgery (SSRF)

CVE-2019-9621 is a server-side request forgery vulnerability in the ProxyServlet component of Zimbra Collaboration Suite (ZCS). It affects ZCS before 8.6 patch 13, 8.7.x before 8.7.11 patch 10, and 8.8.x before 8.8.10 patch 7 or before 8.8.11 patch 3. The flaw allows a remote attacker to cause the Zimbra server to initiate arbitrary requests to internal or external resources through ProxyServlet. Public reporting and vendor references identify the issue specifically as SSRF in ProxyServlet; the provided content does not include lower-level implementation details beyond that component attribution.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an attacker to use the vulnerable Zimbra server as a proxy to reach attacker-chosen internal or external endpoints. The primary impact described in the available sources is confidentiality exposure, including access to sensitive internal resources or data that would not normally be directly reachable by the attacker. The issue may also facilitate further compromise by enabling reconnaissance of internal services and serving as part of a broader exploit chain; reporting in the provided content notes observed exploitation of Zimbra flaws including CVE-2019-9621 to obtain initial access, drop web shells, and support follow-on activity.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, restrict network access to the vulnerable ProxyServlet endpoint as much as operationally feasible, especially from untrusted networks. Apply compensating controls such as reverse-proxy or WAF rules to limit access patterns that can reach ProxyServlet, and constrain the Zimbra server’s outbound connectivity to prevent requests to sensitive internal networks and unnecessary external destinations. Monitor logs for suspicious ProxyServlet access and SSRF-like request patterns, and scan exposed Zimbra instances to confirm exposure and patch status.

Remediation

Patch, then assume compromise.

Upgrade Zimbra Collaboration Suite to a fixed release: 8.6 patch 13 or later, 8.7.11 patch 10 or later for the 8.7.x branch, and 8.8.10 patch 7 or later or 8.8.11 patch 3 or later for the 8.8.x branch, as applicable. After upgrading, verify the deployed version, validate normal mail/proxy functionality, and review vendor security advisories and Bugzilla guidance referenced by Zimbra. Because the vulnerability is listed in CISA KEV with evidence of active exploitation, remediation should be prioritized.
PUBLIC EXPLOITS

Exploits

1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos (1 hidden).

VALID 1 / 2 TOTALView more in app
ZimbraExploitMaturityPoCFrameworkmetasploitVerified exploit

This repository contains two main exploit implementations for CVE-2019-9621 and CVE-2019-9670, targeting Zimbra Collaboration Suite versions 8.5 to 8.7.11 (potentially up to <8.8.11). The exploits leverage an XXE vulnerability in the Autodiscover servlet to extract sensitive configuration (including LDAP credentials), then use those credentials to authenticate and escalate privileges via SSRF to the admin interface. Finally, a JSP webshell is uploaded to the server, granting remote code execution. The repository includes: - Zimbra_Rce.py: A standalone Python script that automates the full exploit chain, from XXE to webshell upload and access. - Zimbra_msf.rb: A Metasploit module implementing the same attack chain, allowing for customizable payloads and integration with the Metasploit framework. - zimbra.dtd: A DTD file used in the XXE attack to extract sensitive configuration files. - README.md: Brief documentation and references. The main attack vector is network-based, requiring access to the Zimbra web interface. The exploit is weaponized, with both standalone and framework-based implementations, and results in remote code execution on the target server. Multiple HTTP endpoints are targeted throughout the attack chain, and the exploit is highly effective against vulnerable Zimbra installations.

k8gegeDisclosed May 6, 2019pythonrubynetwork
EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
ZimbraZimbra Collaboration Suiteapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

17 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence1

Every observed campaign linking this CVE to a named adversary.

Associated malware1

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity10

Community discussion across Reddit, Mastodon, and other social sources.