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.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact Low

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is in the KEV database since March 18, 2026.

The EPSS score is 0.28822.

Exploitation active

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Zimbra Collaboration unaffected
Version Status Constraints
10.0 affected
< 10.0.18
10.1 affected
< 10.1.13

Configuration 1 [-]

OR cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*

No data.

No data.

Subscriptions

Vendors Products
Synacor Subscribe
Zimbra Collaboration Suite Subscribe
Zimbra Subscribe
Collaboration Subscribe

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://wiki.zimbra.com/wiki/Security_Center cve-icon cve-icon
https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.18#Security_Fixes cve-icon cve-icon
https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.13#Security_Fixes cve-icon cve-icon
https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy cve-icon cve-icon
https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories cve-icon cve-icon
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-66376 cve-icon cve-icon
History

Wed, 18 Mar 2026 20:15:00 +0000

Type Values Removed Values Added
First Time appeared Synacor
Synacor zimbra Collaboration Suite
CPEs cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
Vendors & Products Synacor
Synacor zimbra Collaboration Suite

Wed, 18 Mar 2026 17:45:00 +0000

Type Values Removed Values Added
Metrics kev

{'dateAdded': '2026-03-18T00:00:00+00:00', 'dueDate': '2026-04-01T00:00:00+00:00'}

Wed, 18 Mar 2026 17:15:00 +0000

Type Values Removed Values Added
References
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

 ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'active', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 17 Mar 2026 21:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

 ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 06 Jan 2026 00:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 05 Jan 2026 15:00:00 +0000

Type Values Removed Values Added
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.
First Time appeared Zimbra
Zimbra collaboration
Weaknesses CWE-79
CPEs cpe:2.3:a:zimbra:collaboration:*:*:*:*:*:*:*:*
Vendors & Products Zimbra
Zimbra collaboration
References
Metrics cvssV3_1

{'score': 7.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N'}
cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2026-03-19T03:55:17.926Z

Reserved: 2025-11-28T00:00:00.000Z

Link: CVE-2025-66376

cve-icon Vulnrichment

Updated: 2026-01-05T20:42:37.847Z

cve-icon NVD

Status : Analyzed

Published: 2026-01-05T15:15:44.903

Modified: 2026-03-18T20:13:37.087

Link: CVE-2025-66376

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses