CVE-2024-27443

MEDIUM6.1Published on August 12, 2024

An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0. A Cross-Site Scripting (XSS) vulnerability exists in the CalendarInvite feature of the Zimbra webmail classic user interface, because of improper input validation in the handling of the calendar header. An attacker can exploit this via an email message containing a crafted calendar header with an embedded XSS payload. When a victim views this message in the Zimbra webmail classic interface, the payload is executed in the context of the victim's session, potentially leading to execution of arbitrary JavaScript code.

Actively exploited

In the CISA exploited-vulnerabilities catalogue since May 19, 2025
US federal agencies must remediate it by Jun 9, 2025 (BOD 22-01)
First attack observed 275 days after disclosure

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

Source: CISA KEV · Jan 20, 2026 Dec 10, 2025 May 20, 2025 May 19, 2025 May 15, 2025

CVSS score6.1 / 10CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Weakness type (CWE)CWE-79, CWE-79

Vendorszimbra