{
  "id": "CVE-2025-66376",
  "url": "https://spydr.io/cve/CVE-2025-66376",
  "published": "2026-01-05T15:15:44.903Z",
  "modified": "2026-09-30T23:10:00.237Z",
  "score": 6.1,
  "severity": "medium",
  "cvss_version": "3.1",
  "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
  "score_source": "NVD",
  "epss": 0.20227,
  "epss_percentile": 0.97401,
  "exploited": true,
  "kev": {
    "added": "2026-03-18",
    "due": "2026-04-01",
    "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.",
    "ransomware": "Unknown",
    "name": "Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability",
    "notes": "https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories ; https://nvd.nist.gov/vuln/detail/CVE-2025-66376"
  },
  "ssvc_exploitation": "active",
  "vendors": [
    "Zimbra"
  ],
  "products": [
    "Zimbra Collaboration"
  ],
  "cwes": [
    "CWE-79"
  ],
  "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.",
  "status": "Analyzed",
  "score_type": "Primary",
  "scores": {
    "cvss_v40": null,
    "cvss_v31": 6.1,
    "cvss_v30": null
  },
  "references": [
    {
      "url": "https://wiki.zimbra.com/wiki/Security_Center",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.18#Security_Fixes",
      "tags": [
        "Release Notes"
      ]
    },
    {
      "url": "https://wiki.zimbra.com/wiki/Zimbra_Releases/10.1.13#Security_Fixes",
      "tags": [
        "Release Notes"
      ]
    },
    {
      "url": "https://wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy",
      "tags": [
        "Product"
      ]
    },
    {
      "url": "https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories",
      "tags": [
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-66376",
      "tags": [
        "US Government Resource"
      ]
    }
  ],
  "nvd_url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66376",
  "covered_in": [],
  "attribution": [
    {
      "source": "NVD",
      "url": "https://nvd.nist.gov",
      "notice": "This product uses data from the NVD API but is not endorsed or certified by the NVD."
    },
    {
      "source": "CISA KEV",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "notice": "Known exploited vulnerabilities from the CISA KEV catalog."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss",
      "notice": "Exploit prediction scores from FIRST EPSS."
    }
  ]
}