CISA-confirmed known exploited vulnerability

CVE-2024-27443

Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability

Synacor · Zimbra Collaboration Suite (ZCS)

Vulnerability details

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: 2025-05-19

Ransomware campaign use: Unknown

CISA due date: 2025-06-09

Defensive guidance from CISA

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

This is the source's required-action field, not an independently validated patch procedure. Refer to the vendor for exact affected versions and fixes.

Source catalog date: 2026-11-06T19:44:45.1797Z · Last retrieved: 2026-11-06 21:02:26 UTC

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