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CVE-2025-66376Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability
Zimbra Collaboration (ZCS) 10 before 10.0.18 and 10.1 before 10.1.13 allows Classic UI stored XSS via Cascading Style Sheets (CSS) @import directives in an HTML e-mail message.
7.2 HIGHEPSS 20.22%⚡ Known Exploited (CISA KEV)NVD: Analyzed
Overview
Severity
| Score | Severity | Version | Vector String |
|---|---|---|---|
| 7.2 | HIGH | 3.1mitre (CNA) | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N |
| 6.1 | MEDIUM | 3.1NVD | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
CISA required action
⚡ Known exploited · remediation due Apr 1, 2026
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Details
- CVE ID
- CVE-2025-66376
- Status
- Analyzed
- Assigner (CNA)
- mitre
- Published
- Jan 5, 2026
- Last modified
- 2026-10-07 10:10 UTC
- Weaknesses
- CWE-79 · Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')
Affected Products
As published by the CNA in the CVE record.
ZimbraCollaboration2 version ranges
- 10.0 before 10.0.18
- 10.1 before 10.1.13
References
- wiki.zimbra.com https://wiki.zimbra.com/wiki/Security_Center
- wiki.zimbra.com https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.18#Security_Fixes
- wiki.zimbra.com https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.13#Security_Fixes
- wiki.zimbra.com https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy
- wiki.zimbra.com https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
- cisa.gov https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-66376