{
    "id": "CVE-2021-35209",
    "published": "2021-07-02 19:15:08",
    "last_modified": "2026-06-17 03:57:18",
    "cvss_score": "9.8",
    "cvss_severity": "CRITICAL",
    "cvss_version": "3.1",
    "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
    "cwe": "CWE-918",
    "description": "An issue was discovered in ProxyServlet.java in the /proxy servlet in Zimbra Collaboration Suite 8.8 before 8.8.15 Patch 23 and 9.x before 9.0.0 Patch 16. The value of the X-Host header overwrites the value of the Host header in proxied requests. The value of X-Host header is not checked against the whitelist of hosts Zimbra is allowed to proxy to (the zimbraProxyAllowedDomains setting).",
    "epss_score": "0.02995",
    "epss_percentile": "0.86984",
    "kev": 0,
    "kev_due": null,
    "has_exploit": 0,
    "updated_at": "2026-10-11 18:17:26",
    "priority": {
        "rank": 3,
        "label": "In your normal cycle",
        "why": "Critical by CVSS (9.8), but no sign of active exploitation."
    },
    "products": [
        {
            "vendor": "zimbra",
            "product": "collaboration"
        }
    ],
    "kev_detail": null,
    "exploits": [],
    "refs_list": [
        "https://blog.sonarsource.com/zimbra-webmail-compromise-via-email",
        "https://wiki.zimbra.com/wiki/Security_Center",
        "https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23",
        "https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16",
        "https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories",
        "https://blog.sonarsource.com/zimbra-webmail-compromise-via-email",
        "https://wiki.zimbra.com/wiki/Security_Center",
        "https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23",
        "https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16",
        "https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories"
    ]
}