CVE-2025-66376

UNKNOWNKnown Exploited

CISA Known Exploited Vulnerability

https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories ; https://nvd.nist.gov/vuln/detail/CVE-2025-66376

Remediation deadline: April 1, 2026

Description

Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability in the Classic UI where attackers could abuse Cascading Style Sheets (CSS) @import directives in email HTML.

Timeline

Published:March 18th, 2026 12:00 AM

Last modified:March 18th, 2026 12:00 AM

Added to KEV:March 18th, 2026

CVSS Scoring

No CVSS v3 score available

Affected Software

From NVD CPE configuration data

Vendors

Synacor

Products

Zimbra Collaboration Suite (ZCS)

Weaknesses (CWE)

CWE-79

References & Reports

Advisories, patches, and third-party reports

No references available.

Source: CISA KEV + NVD · Data may lag official sources by up to one minute