CVE-2024-27443

CVE-2024-27443 is a medium-severity vulnerability in Zimbra Collaboration with a CVSS 3.x base score of 6.1. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2025-05-19). The underlying weakness is classified as CWE-79.

Key facts

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2024-27443?
CVE-2024-27443 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2024-27443 being actively exploited?
Yes. CVE-2024-27443 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2025-05-19, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2024-27443?
CVE-2024-27443 primarily affects Zimbra Collaboration. In total, 38 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2024-27443?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2024-27443 have an EU (EUVD) identifier?
Yes. CVE-2024-27443 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-24646. It is also flagged as exploited in the EUVD (since 2025-05-19).
When was CVE-2024-27443 published?
CVE-2024-27443 was published on 2024-08-12 and last updated on 2026-06-17.

References

Affected products (38)

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