Synacor Zimbra Collaboration Suite (ZCS): Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability
Synacor Zimbra Collaboration Suite (ZCS)
Zimbra Collaboration contains a cross-site scripting (XSS) vulnerability in the CalendarInvite feature of the Zimbra webmail classic user interface. An attacker can exploit this vulnerability via an email message containing a crafted calendar header, leading to the execution of arbitrary JavaScript code. Added to CISA KEV on 2025-05-19.
Why this severity: CVSS 6.1 (CISA ADP, v3.1); actively exploited (CISA KEV)
- Started
- May 19, 2025
- Closed
- May 19, 2025
Affected
- See vendor advisory / CISA notes (versions not always listed in KEV feed)
Fixed in
- See vendor advisory linked in sources
Timeline1
CISA added CVE-2024-27443 to the KEV catalog (due 2025-06-09).
Advisories5
- Synacor advisory: Synacor Zimbra Collaboration Suite (ZCS)Synacor · May 19, 2025
- Synacor advisory: Synacor Zimbra Collaboration Suite (ZCS)Synacor · May 19, 2025
- Synacor advisory: Synacor Zimbra Collaboration Suite (ZCS)Synacor · May 19, 2025
- NVD: CVE-2024-27443NVD · May 19, 2025
- CISA Known Exploited Vulnerabilities CatalogCISA · May 19, 2025
Notes & caveats
Derived from CISA KEV JSON feed catalogVersion 2026.10.21. CVSS from the CVE record (cvelistV5). 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; many entries are older CVEs newly confirmed as exploited in 2025).
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