highclosedpatched
Synacor Zimbra Collaboration Suite (ZCS): Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability
› Synacor Zimbra Collaboration Suite (ZCS)
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- started
- Mar 18, 2026
- closed
- Mar 18, 2026
- CVEs
- 1
- sources
- 3
## 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. Added to CISA KEV on 2026-03-18.
severity: Actively exploited (CISA KEV)
## cve ids[1]
## affected
- See vendor advisory / CISA notes (versions not always listed in KEV feed)
## fixed in
- See vendor advisory linked in sources
## timeline[1]
CISA added CVE-2025-66376 to the KEV catalog (due 2026-04-01).
## advisories[2]
## news & write-ups[1]
## notes & caveats
Derived from CISA KEV JSON feed catalogVersion 2026.10.21. Exact affected/fixed version strings are not always in the KEV record — verify against the vendor advisory URL. startedAt uses dateAdded (exploitation may have begun earlier).
