CVE record
CVE-2025-66376
Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability
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.
CVE evidence
Known exploitation
Listed in CISA KEV
Absence from the fetched catalog does not establish that exploitation has not occurred.
Severity
high
CVSS 7.2 · CVSS_V3
Affected packages
0
Supported package records returned by OSV. Vendor and product names are not used to infer matches.
CISA Known Exploited Vulnerabilities
Catalog record
- Vendor / project
- Synacor
- Product
- Zimbra Collaboration Suite (ZCS)
- Date added
- Mar 18, 2026
- CISA federal remediation due date
- 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.
- Known ransomware campaign use
- Unknown
- CWE
- CWE-79
OSV package mapping
Affected open-source packages
OSV did not return a package mapping in the five supported ecosystems. RequestGuard does not infer package names from the CISA vendor or product fields.