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CriticalCISA KEVExploited in the wildPublic exploit

XXE in Synacor Zimbra Collaboration Suite mailboxd Autodiscover

IdentifiersCVE-2019-9670CWE-611· Improper Restriction of XML…

CVE-2019-9670 is an XML External Entity (XXE) injection vulnerability in the mailboxd component of Synacor Zimbra Collaboration Suite (ZCS) 8.7.x before 8.7.11p10. The issue is exposed via XML processing in the Autodiscover endpoint, as demonstrated by requests to Autodiscover/Autodiscover.xml. Improper restriction of external entity references allows attacker-supplied XML to be parsed with external entities enabled, which can cause the server to resolve attacker-controlled or local external resources during request processing.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can allow an unauthenticated remote attacker to abuse the vulnerable XML parser to read local files, trigger server-side requests to internal or external resources, and potentially leverage the condition toward arbitrary remote code execution, as reflected in the provided context. At minimum, the flaw can expose sensitive information from the Zimbra server and adjacent internal services; in operational use it has been cited as a high-severity initial access vector.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, restrict or disable exposure of the Autodiscover/Autodiscover.xml endpoint from untrusted networks, place the service behind access controls or reverse-proxy filtering, and inspect/block malicious XML containing DOCTYPE declarations or external entity definitions. Limit outbound connectivity from the Zimbra server to reduce SSRF-style abuse, and monitor mailboxd and web access logs for suspicious Autodiscover requests containing crafted XML payloads.

Remediation

Patch, then assume compromise.

Upgrade Synacor Zimbra Collaboration Suite to 8.7.11 patch 10 or later. Apply the vendor-provided fix for mailboxd XML parsing in the Autodiscover functionality. If the environment is still running affected 8.7.x builds prior to 8.7.11p10, prioritize patching because the vulnerability is known exploited in the wild.
PUBLIC EXPLOITS

Exploits

2 valid exploits after Mallory filtered fakes, detection scripts, and README-only repos.

VALID 2 / 2 TOTALView more in app
Zimbra-RCEMaturityPoCVerified exploit

This repository contains a Python exploit script (zimbra.py) targeting Zimbra Collaboration Suite versions <= 8.7.0 and 8.7.11, exploiting CVE-2019-9670. The exploit leverages an XXE vulnerability in the Autodiscover servlet to extract low-privilege credentials, then uses SSRF via the ProxyServlet to escalate to admin privileges. With the admin token, it uploads an arbitrary file (such as a web shell) to the server, enabling remote code execution. The script requires the attacker to provide a target URL, a DTD file URL (for the XXE payload), a payload file, and a name for the uploaded file. The main code file is zimbra.py, which implements the full exploit chain. The README provides usage instructions and context. No framework is used; this is a standalone operational exploit.

attackgithubDisclosed Aug 16, 2019pythonnetwork
Zimbra-RCEMaturityPoCVerified exploit

This repository contains a Python exploit script (zimbra.py) targeting Zimbra Collaboration Suite versions <= 8.7.0 and 8.7.11, exploiting CVE-2019-9670. The exploit leverages an XXE vulnerability in the Autodiscover servlet to extract low-privilege credentials, then uses SSRF via the ProxyServlet to escalate privileges and obtain an admin token. With this token, it uploads an attacker-supplied file (such as a web shell) to the server using the clientUploader endpoint. The exploit is operational and requires the attacker to provide a DTD payload hosted at a reachable URL, the target Zimbra instance URL, and a file to upload. The README provides usage instructions and argument details. The main code is in zimbra.py, with LICENSE and README.md as supporting files. The exploit is not part of a framework and is a standalone operational exploit for remote code execution on vulnerable Zimbra servers.

rek7Disclosed Aug 16, 2019pythonnetwork
EXPOSURE SURFACE

Affected products & vendors

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VendorProductType
ZimbraZimbra Collaboration Suiteapplication

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Threat actor evidence5

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Detection signatures2

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