What is CVE-2019-9670?

CVE-2019-9670 is a critical-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.8/10. Published 2019-05-29.

How severe is CVE-2019-9670?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2019-9670 known to be exploited?

Yes. CVE-2019-9670 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-01-10), indicating it is being actively exploited. 41 public proof-of-concept repositories are indexed.

XXE in Synacor Zimbra Collaboration Suite

CVE-2019-9670

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.

Vulnerability class: XXE (XML External Entity)

Published 2019-05-29 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 1.000 (100.0th percentile), scored 2026-10-15.

Very high probability of exploitation in the next 30 days — among the top 0.1% most-likely-to-be-exploited CVEs. 100th percentile — 100.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

The 30-day trend appears once there are two daily scores.

Affected products

Synacor Zimbra Collaboration Suite — versions 8.7.11

Weakness classification (CWE)

CWE-611 — Improper Restriction of XML External Entity Reference (XXE)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2022-01-10. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2022-07-10.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

wiki.zimbra.com/wiki/Zimbra_Security_Advisories (Vendor Advisory)
bugzilla.zimbra.com/show_bug.cgi (Patch, Third Party Advisory, Issue Tracking, Broken Link)
www.rapid7.com/db/modules/exploit/linux/http/zimbra_xxe_rce (Third Party Advisory)
packetstormsecurity.com/files/152487/Zimbra-Collaboration-Autodiscover-Servlet-… (Exploit, VDB Entry, Third Party Advisory)
www.exploit-db.com/exploits/46693/ (Exploit, VDB Entry, Third Party Advisory, exploit)
isc.sans.edu/forums/diary/CVE20199670+Zimbra+Collaboration+Suite+XXE+vulnerabil… (Exploit, Third Party Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2019-9670?: CVE-2019-9670 is a critical-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.8/10. Published 2019-05-29.
How severe is CVE-2019-9670?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2019-9670 known to be exploited?: Yes. CVE-2019-9670 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-01-10), indicating it is being actively exploited. 41 public proof-of-concept repositories are indexed.