Vulnerability record

CVE-2019-9670

Synacor Zimbra Collaboration Suite (ZCS) Improper Restriction of XML External Entity Reference

CriticalExploitation confirmedCISA KEV

What should I do?

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Zimbra Collaboration Suite (ZCS), fix it now.

CISA required action: Apply updates per vendor instructions.

US federal civilian agencies must remediate by Jul 10, 2022.

Patch status

Official fix available since Sep 30, 2026

Apply the vendor's update to every affected system. Check the fixed-in versions below where known.

Basis: NVD patch reference

Patch or advisory on bugzilla.zimbra.com (opens in a new tab)

Description

mailboxd component in Synacor Zimbra Collaboration Suite 8.7.x before 8.7.11p10 has an XML External Entity injection (XXE) vulnerability, as demonstrated by Autodiscover/Autodiscover.xml.

Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.

Affected products

Products affected by this vulnerability, with versions and the source of each entry
Product	Vendor	Affected versions	Fixed in	Source
Zimbra Collaboration Suite	Synacor	>= 8.7.0, < 8.7.11; 8.7.11	8.7.11	NVD
Zimbra Collaboration Suite (ZCS)	Synacor	—	—	KEV

Sources: NVD = NIST National Vulnerability Database; KEV = CISA Known Exploited Vulnerabilities catalog.

Intelligence timeline

Developments from the last 30 days, newest first.

CVSS scoredUpdateKEVSep 30, 2026
CVE-2019-9670 scored CVSS 9.8: Synacor Zimbra Collaboration Suite (ZCS), Synacor Zimbra Collaboration Suite (ZCS) Improper Restriction of XML External Entity Reference
CISA lists this as exploited in the wild. Unpatched Zimbra Collaboration Suite (ZCS) systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
Patch releasedUpdateKEVSep 30, 2026
Patch released for CVE-2019-9670: Synacor Zimbra Collaboration Suite (ZCS), Synacor Zimbra Collaboration Suite (ZCS) Improper Restriction of XML External Entity Reference
An official fix is now available for Synacor Zimbra Collaboration Suite (ZCS). This vulnerability is being exploited, so apply it promptly.
Basis: NVD patch reference

1 earlier event is available with a subscription. See plans.

Coverage

We have not published a story about this vulnerability yet.

References

nvd.nist.gov https://nvd.nist.gov/vuln/detail/CVE-2019-9670
packetstormsecurity.com http://packetstormsecurity.com/files/152487/Zimbra-Collaboration-Autodiscover-Servlet-XXE-ProxyServlet-SSRF.ht…
rapid7.com http://www.rapid7.com/db/modules/exploit/linux/http/zimbra_xxe_rce
bugzilla.zimbra.com https://bugzilla.zimbra.com/show_bug.cgi?id=109129
isc.sans.edu https://isc.sans.edu/forums/diary/CVE20199670+Zimbra+Collaboration+Suite+XXE+vulnerability/27570/
wiki.zimbra.com https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
exploit-db.com https://www.exploit-db.com/exploits/46693/
cisa.gov https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-9670