CVE-2025-66376

Published Jan 5, 2026

Last updated 12 hours ago

Exploit known CVSS high 7.2

Overview

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.
Source: cve@mitre.org
NVD status: Analyzed
Products: zimbra_collaboration_suite

Risk scores

CVSS 3.1

Type: Primary
Base score: 6.1
Impact score: 2.7
Exploitability score: 2.8
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Severity: MEDIUM

Known exploits

Data from CISA

Vulnerability name: Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability
Exploit added on: Mar 18, 2026
Exploit action due: Apr 1, 2026
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.

Weaknesses

cve@mitre.org: CWE-79

Hype score is a measure of social media activity compared against trending CVEs from the past 12 months. Max score 100.

Hype score: 13

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "7D423DB3-FCD4-445F-A778-BC5F83E01953",
            "versionEndExcluding": "10.0.18",
            "versionStartIncluding": "10.0.0",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*",
            "matchCriteriaId": "7C3F6B1E-1671-461B-A093-7B6854C227FE",
            "versionEndExcluding": "10.1.13",
            "versionStartIncluding": "10.1.0",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.