CVE-2019-9621

CVE-2019-9621 is a high-severity vulnerability in Synacor Zimbra Collaboration Suite with a CVSS 3.x base score of 7.5. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2025-07-07). The underlying weakness is classified as CWE-918.

Key facts

• Severity: High (CVSS 3.x base score 7.5)
• CVSS v2: 5.0
• EPSS exploit prediction: 81% (100th percentile)
• Actively exploited: Yes — listed in CISA KEV (added 2025-07-07)
• EU (EUVD) id: EUVD-2019-18992
• EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2025-07-07)
• Weakness: CWE-918
• Affected product: Synacor Zimbra Collaboration Suite
• Published: 2019-04-30
• Last modified: 2026-06-17

Description

Zimbra Collaboration Suite 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 8.8.x before 8.8.11 patch 3 allows SSRF via the ProxyServlet component.

Frequently asked questions

What is CVE-2019-9621?

Zimbra Collaboration Suite 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 8.8.x before 8.8.11 patch 3 allows SSRF via the ProxyServlet component.

How severe is CVE-2019-9621?

CVE-2019-9621 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2019-9621 being actively exploited?

Yes. CVE-2019-9621 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2025-07-07, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2019-9621?

CVE-2019-9621 primarily affects Synacor Zimbra Collaboration Suite. In total, 46 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-9621?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2019-9621 have an EU (EUVD) identifier?

Yes. CVE-2019-9621 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2019-18992. It is also flagged as exploited in the EUVD (since 2025-07-07).

When was CVE-2019-9621 published?

CVE-2019-9621 was published on 2019-04-30 and last updated on 2026-06-17.

References

• http://packetstormsecurity.com/files/152487/Zimbra-Collaboration-Autodiscover-Servlet-XXE-ProxyServlet-SSRF.html
• http://packetstormsecurity.com/files/153190/Zimbra-XML-Injection-Server-Side-Request-Forgery.html
• http://www.rapid7.com/db/modules/exploit/linux/http/zimbra_xxe_rce
• https://blog.tint0.com/2019/03/a-saga-of-code-executions-on-zimbra.html
• https://blog.zimbra.com/2019/03/9826/
• https://bugzilla.zimbra.com/show_bug.cgi?id=109127
• https://wiki.zimbra.com/wiki/Security_Center
• https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
• https://www.exploit-db.com/exploits/46693/
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-9621

Affected products (46)

• cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:-:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch1:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch10:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch11:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch12:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch2:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch3:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch4:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch5:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch6:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch7:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch8:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.6.0:patch9:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:-:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch1:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch10:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch2:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch3:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch4:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch5:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch6:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch7:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch8:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.7.11:patch9:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:-:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:p5:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:patch1:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:patch2:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:patch3:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:patch4:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:patch6:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:patch7:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:patch8:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.9:patch9:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.10:-:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.10:patch1:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.10:patch2:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.10:patch3:*:*:*:*:*:*
• cpe:2.3:a:synacor:zimbra_collaboration_suite:8.8.10:patch4:*:*:*:*:*:*

More vulnerabilities in Synacor Zimbra Collaboration Suite

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• CVE-2022-37042 — Critical (CVSS 9.8): Zimbra Collaboration Suite (ZCS) 8.8.15 and 9.0 has mboximport functionality that receives a ZIP archive and extracts…
• CVE-2020-7796 — Critical (CVSS 9.8): Zimbra Collaboration Suite (ZCS) before 8.8.15 Patch 7 allows SSRF when WebEx zimlet is installed and zimlet JSP is…
• CVE-2019-9670 — Critical (CVSS 9.8): mailboxd component in Synacor Zimbra Collaboration Suite 8.7.x before 8.7.11p10 has an XML External Entity injection…
• CVE-2019-6980 — Critical (CVSS 9.8): Synacor Zimbra Collaboration Suite 8.7.x through 8.8.11 allows insecure object deserialization in the IMAP component.

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