ACTIVELY EXPLOITED

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

Facts
VendorSynacor
ProductZimbra Collaboration Suite (ZCS)
Actively exploitedYes
Added to CISA KEV10 Jan 2022
CISA federal deadline10 Jul 2022
Weakness (CWE)CWE-611

Required action (CISA's text)

Apply updates per vendor instructions.

Description (NVD)

Synacor Zimbra Collaboration Suite (ZCS) contains an improper restriction of XML external entity (XXE) vulnerability in the mailboxd component.

SOURCES

Other Synacor flaws

Data from NVD, CISA KEV, FIRST EPSS and vendor advisories. Updated 10 Nov 2026.