- Medium 6.1
- Known exploited (CISA KEV)
CVE-2025-66376
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.
Scores
The facts
- Published
- 5 January 2026
- Last changed
- 7 October 2026
- NVD status
- Analyzed
- Severity
- Medium, CVSS 6.1 out of 10 (version 3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- Affects
- synacor zimbra collaboration suite
- Known exploited
- Yes. CISA added it to the Known Exploited Vulnerabilities catalogue on 18 March 2026.
- EPSS
- 20.2% chance of exploitation activity in the next 30 days (percentile 97).
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