CVEs / CVE-2024-27443
CVE-2024-27443: Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability
- Known exploited in the CISA KEV catalog since 19 May 2025
- medium 6.1 CVSS 3.1 (NVD)
- EPSS 24.6% chance of exploitation in the next 30 days, higher than 97% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Zimbra Collaboration contains a cross-site scripting (XSS) vulnerability in the CalendarInvite feature of the Zimbra webmail classic user interface. An attacker can exploit this vulnerability via an email message containing a crafted calendar header, leading to the execution of arbitrary JavaScript code.
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 and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| n/a n/a | n/a | — |
Exploitation
| In CISA KEV since | 19 May 2025 |
|---|---|
| Due date for US federal agencies | 9 Jun 2025 |
| Used in ransomware campaigns | Unknown |
| 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. |
Severity
| CVSS 3.1 | 6.1 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NScored by NVD |
|---|---|
| Weakness | CWE-79 |
References
- CVE-2024-27443 on NVD
- CVE-2024-27443 in the CISA KEV catalog
- https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P46#Security_Fixes (cited by CISA)
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P39#Security_Fixes (cited by CISA)
- https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.7#Security_Fixes (cited by CISA)
- CVE-2024-27443 on OSV
- https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.7#Security_Fixes Release Notes
- https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P39#Security_Fixes Release Notes
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-27443 US Government Resource
- https://www.welivesecurity.com/en/eset-research/operation-roundpress/ Press/Media Coverage
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.