CVE-2025-66376
7.2 · HIGH Actively ExploitedOverview
CVE-2025-66376 is a high-severity vulnerability affecting synacor zimbra_collaboration_suite. It was published on January 5, 2026 and has a CVSS 3.1 base score of 7.2 (HIGH). This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.
This vulnerability has a CVSS 3.1 base score of 7.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
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.
Remediation
Check the references section for vendor advisories and patches from synacor. Update zimbra_collaboration_suite to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| synacor | zimbra_collaboration_suite | >= 10.0.0, < 10.0.18 | Affected |
References
Frequently Asked Questions
What is CVE-2025-66376?
CVE-2025-66376 is a high-severity vulnerability affecting synacor zimbra_collaboration_suite. It was published on January 5, 2026 and has a CVSS 3.1 base score of 7.2 (HIGH). This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild.
How severe is CVE-2025-66376?
This vulnerability has a CVSS 3.1 base score of 7.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2025-66376?
Check the references section for vendor advisories and patches from synacor. Update zimbra_collaboration_suite to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2025-66376?
CyberStrike's AI-powered security agents can automatically detect CVE-2025-66376 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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