CVE Watch—

CVE-2024-27443

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

CVSS

—

No CVSS

EPSS

24.6%

p98

KEV

YES

May 19, 2025

Exploit Today

0-100

Published: — · Last modified: —

EPSS · 30d

23.6%EPSS · 30 days24.6%

2026-09-162026-10-14

KEV catalog record

Product

Synacor / Zimbra Collaboration Suite (ZCS)

Vulnerability

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

Added to KEV

May 19, 2025

Remediate by

Jun 9, 2025

Known ransomware use

Summary description

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.

Required action

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

Notes

https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P46#Security_Fixes ; https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P39#Security_Fixes ; https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.7#Security_Fixes ; https://nvd.nist.gov/vuln/detail/CVE-2024-27443

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