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CVE-2025-66376

Published: Jan 5, 2026Updated: Jan 8, 2026 Sources: CVE List NVD BDUCWE-79
NVD MITRE
7.2CVSSHIGH
EPSS Score
12.0%
Top 4.4%
CISA KEV
Active Exploitation
Since Mar 18, 2026
Exploits
No Known Exploits
Remediation
Patch Available

Description

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:CC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

CWE-79

Affected Products

CollaborationZimbra
On-premDesktop App
Enterprise Software / collaboration-groupware
Zimbra Collaboration SuiteZimbra Inc.
Mixed
Communications / email-server-client
zimbracommercialEnterprise Softwareaka zimbra collaboration server
zimbra inc.commercialUSCommunications

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

CISA Known Exploited Vulnerability
Added to KEV:Mar 18, 2026
Remediation due:Apr 1, 2026

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.

Official Patch Available

MITRE ATT&CK

2 techniques
Execution
Initial Access
View detailed technique mapping

References

https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
wiki.zimbra.com
https://wiki.zimbra.com/wiki/Security_Center
wiki.zimbra.com
https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy
wiki.zimbra.com
and 3 more references View all →

Timeline

Published
Jan 5, 2026
Last Updated
Jan 8, 2026
Added to CISA KEV
Mar 18, 2026

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