CVE-2026-33371: Synacor Zimbra Collaboration Suite

Medium severity, CVSS 4.3. EPSS: 0.4% chance of exploitation in the next 30 days.

An issue was discovered in Zimbra Collaboration (ZCS) 10.0 and 10.1. An XML External Entity (XXE) vulnerability exists in the Zimbra Exchange Web Services (EWS) SOAP interface due to improper handling of XML input. An authenticated attacker can submit crafted XML data that is processed by an XML parser with external entity resolution enabled. Successful exploitation may allow disclosure of sensitive local files from the server.

Affected products

• Synacor Zimbra Collaboration Suite: from 10.0.0, before 10.1.16 (fixed in 10.1.16)

Published 2026-03-20. Last modified 2026-06-17.