Disclosure summary
Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability in the Classic UI where attackers could abuse Cascading Style Sheets (CSS) @import directives in email HTML.
CISA remediation guidance
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Original records & references
PUBLISHED 2026-03-18T00:00:00-04:00
MODIFIED 2026-03-18T00:00:00-04:00
INGESTED 2026-10-06T11:42:57-04:00