Actively exploited · Published Aug 12, 2024 · Assigned by mitre
CVE-2024-27443
Medium 6.1 Exploited
In plain English
A medium-severity cross-site scripting in Zimbra Collaboration Suite (ZCS) from Synacor. Attackers are actively exploiting it in the wild (listed by CISA on May 19, 2025). The chance it is exploited in the next 30 days is estimated at 24.6% (higher than 98% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA guidance
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Federal agencies must remediate by Jun 9, 2025.
Official 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.
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
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.welivesecurity.com/en/eset-research/operation-roundpress/ third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-27443 government-resource