CVE DATABASE / CVE-2024-27443
CVE-2024-27443
Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability
Confirmed exploited in the wild. Added 2025-05-19.
Federal remediation due 2025-06-09.
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.
Summary
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.
CVSS 3.1 breakdown
| Base score | 6.1 (MEDIUM) |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| Attack vector | NETWORK |
| Attack complexity | LOW |
| Privileges required | NONE |
| User interaction | REQUIRED |
| Scope | CHANGED |
| Confidentiality | LOW |
| Integrity | LOW |
| Availability | NONE |
Weakness type (CWE)
Affected products
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References
- https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.7#Security_Fixes
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P39#Security_Fixes
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-27443
- https://www.welivesecurity.com/en/eset-research/operation-roundpress/
Data: NIST NVD + CISA KEV. NVD last modified 2025-10-31. Always verify against the vendor advisory before acting.