Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability (CVE-2024-27443)
Severity: medium · Patch status: unknown · Since 2025-05-19 · CVE-2024-27443
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. CISA added CVE-2024-27443 to its Known Exploited Vulnerabilities catalog on May 19, 2025, which means attackers are exploiting it in the wild.
What to do
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- US federal agencies must remediate by Jun 9, 2025 (BOD 22-01); treat that as the outer limit.
Sources
All live incidents on Threat Watch