CVE-2025-66376
Act now ● On CISA KEV — actively exploited
Actively exploited — on the CISA KEV list.
CVSS base
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EPSS — probability of exploitation (30 days)
19.6%
97.3th percentile
CISA KEV
Listed
Added 2026-03-18 · patch by 2026-04-01
Weakness / dates
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Published — · modified —
Timeline
- 2026-03-18 — Added to CISA KEV (actively exploited)
- 2026-04-01 — CISA patch-by deadline
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.