CVE-2025-66376 kev in the critical feed json
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…
published 2026-01-05 10 mo ago modified 2026-10-07 33 d ago also EUVD-2026-0850
- cvss
- 7.2
- version 3.1, CNA
- cisa kev
- Exploited
- added 2026-03-18
- epss
- 20.2%
- EPSS 20.2% chance of exploitation in 30 days, percentile 97%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
cisa 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.
- Zimbra Collaboration 10.0.18, 10.1.13
Timeline
- Published
- CISA SSVC: exploitation active
- Added to CISA KEV
- CISA patch deadline
Known exploited
- Added
- 7 mo ago
- Patch by
- 2026-04-01 (7 mo ago)
- Ransomware
- Not known
- 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.
- Vendor, product
- Synacor, Zimbra Collaboration Suite (ZCS)
- CISA name
- Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability
CISA SSVC
- Exploitation
- Active, exploited in the wild
- Automatable
- no
- Technical impact
- partial
- Assessed
- 7 mo ago
Exploit prediction
20.23% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.2 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N |
| NVD | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
Affected products
- Zimbra Collaboration
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
wiki.zimbra.com
/wiki/Zimbra_Security_Advisories
vendor-advisory
-
wiki.zimbra.com
/wiki/Security_Center
release-notes, vendor-advisory
-
wiki.zimbra.com
/wiki/Zimbra_Responsible_Disclosure_Policy
product
-
wiki.zimbra.com
/wiki/Zimbra_Releases/10.1.13#Security_Fixes
release-notes
-
wiki.zimbra.com
/wiki/Zimbra_Releases/10.0.18#Security_Fixes
release-notes
-
cisa.gov
/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-66376
government-resource, us-government-resource
Sources
- CVE List CVE-2025-66376
- NVD CVE-2025-66376
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