CVE-2025-66376 — Actively Exploited: Zimbra Collaboration Suite (ZCS) (Synacor)
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 ID | CVE-2025-66376 |
|---|---|
| Vendor | Synacor |
| Product | Zimbra Collaboration Suite (ZCS) |
| Vulnerability name | Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability |
| Date added | 2026-03-18 |
| Remediation due | 2026-04-01 |
| Known ransomware use | Unknown |
| 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. |
| 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. |
| Source | CISA Known Exploited Vulnerabilities |
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