Security Resilience

CVE-2019-9670

XXE in Synacor Zimbra Collaboration Suite 8.7.0 – 8.7.11

CISA KEVActive ExploitationEUVD ExploitedPublic PoCXXE
Published
29 May 2019
Modified
04 November 2025
KEV Added
10 January 2022
Patch / advisory
View advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.99 100.0th percentile
Risk Priority 97 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2019-9670 is a critical-severity Improper Restriction of XML External Entity Reference (CWE-611) vulnerability in Synacor Zimbra Collaboration Suite. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked in the top 0.0% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

The vulnerability is an XML External Entity injection (XXE) flaw, tracked as CWE-611, affecting the mailboxd component in Synacor Zimbra Collaboration Suite versions 8.7.x prior to 8.7.11p10. It is demonstrated through the Autodiscover/Autodiscover.xml endpoint and carries a CVSS 3.1 base score of 9.8.

An unauthenticated attacker with network access can supply malicious XML to the Autodiscover servlet, enabling arbitrary file disclosure, server-side request forgery, or further code execution on the affected server. Public exploit code and a Metasploit module have been published that chain the XXE into remote command execution.

Zimbra security advisories and the associated bug report direct administrators to upgrade to version 8.7.11p10 or later; the SANS Internet Storm Center diary also references the vendor patch as the primary remediation.

Public exploit modules and detailed technical write-ups appeared shortly after disclosure, confirming that the issue is readily exploitable in default installations.

OWASP Top 10 for Web (2025)

A02:2025 Security Misconfiguration

EU & UK References

Vulnerability Data

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.

CWE(s)
CWE-611
KEV Date Added
10 January 2022

Related Threats

Threat-Actor AttributionAI

CrowdStrike (McAfee / Symantec civil claims)
Understanding and Mitigating Russian State-Sponsored Cyber Threats to U.S. Critical Infrastructure | CISA
Microsoft Corp. (Salesforce / Slack engineer recruitment claims)
Understanding and Mitigating Russian State-Sponsored Cyber Threats to U.S. Critical Infrastructure | CISA
APT28 (G0007)
Understanding and Mitigating Russian State-Sponsored Cyber Threats to U.S. Critical Infrastructure | CISA
APT29 (G0016)
Understanding and Mitigating Russian State-Sponsored Cyber Threats to U.S. Critical Infrastructure | CISA
Sandworm Team (G0034)
Understanding and Mitigating Russian State-Sponsored Cyber Threats to U.S. Critical Infrastructure | CISA
Dragonfly (G0035)
Understanding and Mitigating Russian State-Sponsored Cyber Threats to U.S. Critical Infrastructure | CISA
AnonOps
Understanding and Mitigating Russian State-Sponsored Cyber Threats to U.S. Critical Infrastructure | CISA

MITRE ATT&CK Enterprise Techniques

T1001 Data Obfuscation Command And Control
Adversaries may obfuscate command and control traffic to make it more difficult to detect.
attack.mitre.org →
T1003 OS Credential Dumping Credential Access
Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password.
attack.mitre.org →
T1003.001 LSASS Memory Credential Access
Adversaries may attempt to access credential material stored in the process memory of the Local Security Authority Subsystem Service (LSASS).
attack.mitre.org →
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
attack.mitre.org →
T1003.007 Proc Filesystem Credential Access
Adversaries may gather credentials from the proc filesystem or `/proc`.
attack.mitre.org →
T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-33371Same product: Synacor Zimbra Collaboration Suite
CVE-2019-9621Same product: Synacor Zimbra Collaboration Suiteboth on KEV
CVE-2022-27926Same product: Synacor Zimbra Collaboration Suiteboth on KEV
CVE-2023-34192Same product: Synacor Zimbra Collaboration Suiteboth on KEV
CVE-2026-73570Same product: Synacor Zimbra Collaboration Suiteboth on KEV
CVE-2025-27915Same product: Synacor Zimbra Collaboration Suiteboth on KEV
CVE-2024-45519Same product: Synacor Zimbra Collaboration Suiteboth on KEV
CVE-2022-41352Same product: Synacor Zimbra Collaboration Suiteboth on KEV
CVE-2023-37580Same product: Synacor Zimbra Collaboration Suiteboth on KEV
CVE-2022-27924Same product: Synacor Zimbra Collaboration Suiteboth on KEV

Affected Assets

synacor
zimbra collaboration suite
8.7.11 · 8.7.0 — 8.7.11

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.5.1
  • V15.3.2

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CA-8 Penetration Testing
addresses: CWE-611

Penetration testing includes XML external entity payloads, detecting XXE vulnerabilities and enabling their mitigation.

SI-4 System Monitoring
addresses: CWE-611

Identifies XML external entity processing via monitoring of unusual file/network access or resource usage.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

ID.RA-01 partial match
blocks

Vulnerability scanning can discover XXE flaws but does not prevent their introduction in code.

PR.PS-01 partial match
blocks

Hardened XML parser configurations directly disable external entity resolution.

PR.PS-02 partial match
blocks

Patching eliminates XXE-vulnerable parser versions but is only one aspect of software maintenance.

PR.PS-06 partial match
blocks

Secure SDLC practices include input validation and safe XML parser configuration that prevent XXE.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.5.32 Intellectual property rights partial match
removes

References