HIGH Actively exploited CWE-79
CVE-2025-66376
Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability
Synacor·Zimbra Collaboration Suite (ZCS)
7.2/ 10
CVSS 3.1
High severity
20%
EPSS exploit odds
Chance of exploitation in the next 30 days
Higher than 98% of all CVEs
Listed
CISA KEV catalog
- Added
- Mar 18, 2026
- Fix due
- Apr 1, 2026
- Ransomware
- Not known
Timeline
- Published
- Jan 5, 2026
- Updated
- Mar 19, 2026
- First covered
- Jul 10, 2026
- Latest story
- 4 months ago
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.
CWE-79Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')
Attack profile
Attack vectorNetwork
ComplexityLow
PrivilegesNone
User interactionNone
ScopeChanged
ConfidentialityLow
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:NCISA 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.
Affected products
- Zimbra Collaboration10.0 to before 10.0.1810.1 to before 10.1.13