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PatchSiren cyber security CVE debrief

CVE-2019-9670 Synacor CVE debrief

CVE-2019-9670 is a Synacor Zimbra Collaboration Suite (ZCS) vulnerability described as an improper restriction of XML External Entity (XXE) reference handling. CISA has placed it in the Known Exploited Vulnerabilities catalog, so defenders should treat it as a high-priority patching item and follow vendor update guidance.

Vendor
Synacor
Product
Zimbra Collaboration Suite (ZCS)
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2022-01-10
Original CVE updated
2022-01-10
Advisory published
2022-01-10
Advisory updated
2022-01-10

Who should care

Administrators, security teams, and patch managers responsible for Synacor Zimbra Collaboration Suite (ZCS) deployments should prioritize this CVE, especially where ZCS is relied on for business-critical mail and collaboration services.

Technical summary

The issue is classified as an XML External Entity (XXE) weakness, meaning XML input handling in ZCS did not sufficiently restrict external entity processing. The supplied corpus does not include affected version ranges or exploit details, but the vulnerability is officially recognized by CISA as known exploited and mapped to vendor-directed updates.

Defensive priority

High

Recommended defensive actions

  • Inventory all Synacor Zimbra Collaboration Suite (ZCS) instances and confirm which ones are exposed or mission-critical.
  • Apply vendor-recommended updates or patches as directed by Synacor and CISA.
  • Verify remediation by checking installed versions and change records after patching.
  • Review XML-processing surfaces in ZCS-related integrations and disable unnecessary XML features where vendor guidance allows.
  • Monitor logs and security alerts for abnormal requests or behavior associated with ZCS.
  • Track CISA KEV deadlines and ensure remediation is completed before or by the applicable due date where possible.

Evidence notes

This debrief is based on the supplied CISA KEV source item, which identifies CVE-2019-9670 as affecting Synacor Zimbra Collaboration Suite (ZCS) and labels it an improper restriction of XML External Entity Reference. The source item states the required action is to apply updates per vendor instructions and marks the vulnerability as known exploited. Official reference links supplied with the corpus include the CVE.org record, NVD detail page, and CISA KEV catalog.

Official resources

CISA KEV listing indicates known exploitation; the supplied corpus does not include exploit code, affected-version specifics, or vendor advisory text.