What is CVE-2019-9670?

CVE-2019-9670 is Synacor Zimbra Collaboration Suite (ZCS) Improper Restriction of XML External Entity Reference. The supplied enrichment data classifies it as Injection mapped to CWE-611 XML External Entity Reference.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Yes: CISA KEV signal present. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

Yes. The supplied enrichment data lists CVE-2019-9670 in CISA KEV with required action: Apply updates per vendor instructions.. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

Is there a public exploit?

58 public PoC repositories reported; 2 marked weaponized in current dataset. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS, database audit logs where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2019-9670 using CVSS 9.8, EPSS 100%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

The supplied mitigation guidance says to apply vendor patches and restrict external exposure until fixed. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

Publicly linked actor or ransomware signals in the supplied enrichment data: Earth Lusca (), APT 29 (), TeamTNT (), Kinsing (). Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Treat as emergency remediation because CISA KEV status is present. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

CISA KEVcriticalInjectionpublic exploit

CVE-2019-9670

CVE-2019-9670 — Synacor Zimbra Collaboration Suite (ZCS) Improper Restriction of XML External Entity Reference

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.

Published May 29, 2019Updated Jun 17, 2026Sources: NVD, Synacor (CNA), CISA, FIRST EPSS, GitHub, Exploit-DB, SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Confirmed

CISA KEV, listed Jan 10, 2022

EPSS

100%

top of FIRST's scoreset

Affects

Synacor

Zimbra Collaboration Suite (ZCS)

CVSS base

9.8

critical · 2 sources

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

Active

none · proof-of-concept · active

Automatable

Yes

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

The vendor's own words where we have them.

Upgrade Zimbra Collaboration Suite (ZCS) to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

CISA required action

Apply updates per vendor instructions.

Federal deadline Jul 10, 2022 — passed 1,527 days ago

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Treat as emergency remediation because CISA KEV status is present.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
Synacor	Zimbra Collaboration Suite (ZCS)	—	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

High

Confidentiality

High

Integrity

High

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Network

Privileges Req

None

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
9.8	CVSS 3.1	critical	3.9	5.9	NVD, CNA
7.5	CVSS 2.0	high	10	6.4	NVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-611 · Improper Restriction of XML External Entity Reference

Read Application Data
Read Files or Directories
Bypass Protection Mechanism
DoS: Resource Consumption (CPU)

Mitigation: Many XML parsers and validators can be configured to disable external entity expansion.::

Weakness & attack patterns

CWE-611XML External Entity Reference

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-221 · Data Serialization External Entities Blowup

CISA KEV details

CISA lists a CVE here once it has evidence of exploitation against real targets.

CISAThat month →

Listed

Jan 10, 2022

Federal deadline

Jul 10, 2022

passed 1,527 days ago

Ransomware use

Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a date to argue against.

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

2 of the 5 sampled are weaponized

Exploit entries

Exploit-DB and CTI exploit indexes

Malware

Families a CTI source ties to this CVE. One named, with the total it tracks.

Families tracked

Named

Cobalt Strike

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Search application, proxy, and WAF logs for requests touching /Autodiscover.xml.
Prioritize edge telemetry for network-reachable Zimbra Collaboration Suite (ZCS).
Monitor for scanner or exploit-pattern traffic after 58 public PoC repositories were reported.

web/proxy/WAF logsapplication logsnetwork IDS/IPSdatabase audit logs

Groups associated with this CVE

Groups reported in connection with this vulnerability. A reported association, not a confirmed observation of that group using it — and not scoped to any sector or campaign.

Earth LuscaAPT 29TeamTNTKinsing

hash334e32e7eea638089a7259c594d87db965
SOCRadar Threat Exchange Services · Jul 11, 2026
hashb05579c5144602216ce0787cf1161bb60a67e9e265
SOCRadar Threat Exchange Services · Jul 11, 2026
hash49152:deurfqriidw7kamngrs7qibb8gdcdomsu+zomwghvls3uewtzkcfz6gc7ppyziil:c+vq5pmgcpv+
SOCRadar Threat Exchange Services · Jun 29, 2026

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 9.8 (AV:N)
Jun 17, 2026 · NVD
2025
Bulletin released on Mitre.
Jul 28, 2025 · SOCRadar CTI
Cve is exploited Synacor Zimbra Collaboration Suite (ZCS) Improper Restriction of XML External Entity Reference
Mar 12, 2025 · SOCRadar CTI
Bulletin released on NIST.
Feb 7, 2025 · SOCRadar CTI
2024
Bulletin released on NIST.
Jul 24, 2024 · SOCRadar CTI
CVE is exploited. "lions2012/Penetration_Testing_POC"
Feb 8, 2024 · SOCRadar CTI
2023
CVE is exploited. "Ostorlab/KEV"
Dec 26, 2023 · SOCRadar CTI
CVE is exploited. "0xT11/CVE-POC"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "ARPSyndicate/cvemon"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "HimmelAward/Goby_POC"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "Mr-xn/Penetration_Testing_POC"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "Ostorlab/known_exploited_vulnerbilities_detectors"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "developer3000S/PoC-in-GitHub"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "hectorgie/PoC-in-GitHub"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "nth347/Zimbra-RCE-exploit"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "oppsec/arbimz"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "oppsec/zaber"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "raylax/rayx"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "rek7/Zimbra-RCE"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "ugur-ercan/exploit-collection"
Dec 14, 2023 · SOCRadar CTI
CVE is exploited. "xuetusummer/Penetration_Testing_POC"
Dec 14, 2023 · SOCRadar CTI
2022
Added to CISA KEV catalog
Jan 10, 2022 · CISA
2019
Initial · CVE published
May 29, 2019 · NVD
Added · Verified remote entry: Zimbra Collaboration - Autodiscover Servlet XXE and ProxyServlet SSRF (Metasploit)
Apr 12, 2019 · Exploit-DB
Added · Verified remote entry: Zimbra Collaboration - Autodiscover Servlet XXE and ProxyServlet SSRF (Metasploit)
Apr 12, 2019 · Exploit-DB
Added · Verified remote entry: Zimbra Collaboration - Autodiscover Servlet XXE and ProxyServlet SSRF (Metasploit)
Apr 12, 2019 · Exploit-DB

Source activity

Readings a source repeats on a schedule, counted rather than listed.

4×ModifiedJul 24, 2024 – Feb 25, 2025 · SOCRadar CTI
4×Github ReposDec 17, 2023 – May 5, 2024 · SOCRadar CTI
1×SVRS is calculatedMay 5, 2024 · SOCRadar CTI

References

8 on the record

packetstormsecurity.com/files/152487/Zimbra-Collaboration-Autodiscover-Servlet-XXE-ProxyServlet-SSRF.html
Exploit, Third Party Advisory, VDB Entry, NIST, MITRE_REFERENCES, GITHUB
www.rapid7.com/db/modules/exploit/linux/http/zimbra_xxe_rce
Third Party Advisory, NIST, MITRE_REFERENCES
bugzilla.zimbra.com/show_bug.cgi?id=109129
Broken Link, Issue Tracking, Patch, Third Party Advisory, NIST, MITRE_REFERENCES
isc.sans.edu/forums/diary/CVE20199670+Zimbra+Collaboration+Suite+XXE+vulnerability/27570/
Exploit, Third Party Advisory, NIST
wiki.zimbra.com/wiki/Zimbra_Security_Advisories
Vendor Advisory, NIST, MITRE_REFERENCES
www.exploit-db.com/exploits/46693/
Exploit, Third Party Advisory, VDB Entry, Vendor Advisory, Mitre, NIST, GITHUB
www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-9670
US Government Resource
nvd.nist.gov/vuln/detail/CVE-2019-9670
Vendor Advisory

Elsewhere on this site

Synacorevery CVE for this vendor
January 2022what else CISA listed
Injectionsame class
CWE-611other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

Only the 3 indicator(s) reported for this CVE are available; no packet-level or host-forensic artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2019-9670 is Synacor Zimbra Collaboration Suite (ZCS) Improper Restriction of XML External Entity Reference, a critical vulnerability affecting Zimbra Collaboration Suite (ZCS) from Synacor. The current evidence lists it in CISA KEV, and the exploit status is: Yes: CISA KEV signal present. Public exploit evidence is: 58 public PoC repositories reported; 2 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 9.8 describes technical severity, while EPSS 100% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.