XXE in Synacor Zimbra Collaboration Suite mailboxd Autodiscover
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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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.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
2 valid exploits after Mallory filtered fakes, detection scripts, and README-only repos.
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.
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.
Affected products & vendors
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Recent activity
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An XXE-related vulnerability in Synacor Zimbra Collaboration Suite that the content states APT29 exploited.
A specific vulnerability (CVE-2019-9670) associated with exploitation or targeting by the Cozy Bear (APT29) threat actor.
A specific vulnerability (CVE-2019-9670) associated with exploitation or targeting by the Cozy Bear (APT29) threat actor.
A vulnerability in Zimbra software that APT29 exploited to gain access.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.