What is CVE-2024-27443?

CVE-2024-27443 is a medium-severity vulnerability in Zimbra Collaboration, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2024-08-12.

How severe is CVE-2024-27443?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Is CVE-2024-27443 known to be exploited?

Yes. CVE-2024-27443 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-05-19), indicating it is being actively exploited. 5 public proof-of-concept repositories are indexed.

XSS in Zimbra Collaboration

CVE-2024-27443

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.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.236 (97.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 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.

Affected products

Zimbra Collaboration — versions 9.0.0
N/a — versions n/a

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2025-05-19. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 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.

Public proof-of-concept exploits

References

cve@mitre.org (Release Notes)
cve@mitre.org (Release Notes)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (Press/Media Coverage)

Frequently asked questions

What is CVE-2024-27443?: CVE-2024-27443 is a medium-severity vulnerability in Zimbra Collaboration, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2024-08-12.
How severe is CVE-2024-27443?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2024-27443 known to be exploited?: Yes. CVE-2024-27443 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-05-19), indicating it is being actively exploited. 5 public proof-of-concept repositories are indexed.