{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "hMailServer",
          "repo": "https://gitlab.com/hmailserver/hmailserver",
          "vendor": "Progressive Robot Ltd",
          "versions": [
            {
              "lessThanOrEqual": "6.3.6",
              "status": "affected",
              "version": "6.0.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Found in the hMailServer project\u0027s own security review (Progressive Robot Ltd)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Insufficient preservation of the original sender in the forwarding of Progressive Robot hMailServer 6.0.0 through 6.3.6 allows a remote unauthenticated attacker to have mail they write, naming in its From an address at a domain the server hosts, delivered to other receivers as passing that domain\u0027s DMARC policy. When the server sent on a copy of mail that came from outside - an account\u0027s forward, a mail rule\u0027s forward, a Sieve redirect, a list\u0027s copy, or an alias or list expanding to an outside address - it could give the copy an SMTP identity in the organisation of the domain the copy\u0027s From names, whatever the message\u0027s origin: with the Sender Rewriting Scheme or the rewrite of the envelope sender on forwarding enabled (both off by default), an address at the forwarding domain; for a list, its bounce address; for a message with an empty envelope sender, none, under the server\u0027s own host name; and an envelope sender the message came with at a subdomain of a hosted domain was kept. Where that identity\u0027s SPF record authorises the server, other receivers\u0027 SPF check of the copy passed for a domain aligned with the From, and DMARC passed with it, although the message had not passed DMARC when the server received it. Exploitation needs a forward, redirect, alias or list that carries the hosted domain\u0027s mail to an outside address, and one of: SRS or the envelope rewrite enabled; a list whose bounce address is in the domain\u0027s organisation; an envelope sender at a subdomain whose SPF record authorises the server; or, for an empty envelope sender, an SPF record that authorises the server under its host name. The DKIM route to the same result is CVE-2026-107567."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-441",
              "description": "CWE-441: Unintended Proxy or Intermediary (\u0027Confused Deputy\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T15:12:35.847Z",
        "orgId": "ceab7361-8a18-47b1-92ba-4d7d25f6715a",
        "shortName": "GitLab"
      },
      "references": [
        {
          "url": "https://gitlab.com/hmailserver/hmailserver/-/work_items/90"
        },
        {
          "url": "https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.7"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade to hMailServer 6.3.7, in which a copy of mail from outside is sent on with an envelope sender, or under a host name, in the organisation of a domain its From names only when the message passed DMARC for that organisation when it arrived, a pass every copy of the message carries. Otherwise a forward, a Sieve redirect or a rule\u0027s forward keeps the envelope sender the message came with rather than an SRS or rewritten one; a copy whose identity would still be in that organisation - an empty envelope sender under a host name of it, or an envelope sender at the server\u0027s host name or in a hosted domain\u0027s organisation - is not sent to an outside address, nor is the message where an alias or a list expands to one; a managed list does not distribute the posting; and a distribution list\u0027s bounce address is not applied to it. Until then: keep SRS and the rewrite of the envelope sender on forwarding off where they are not needed; turn on the account option not to forward messages flagged as spam (ForwardAbortSpamFlagged) for accounts that forward to outside addresses, which does not hold a Sieve redirect; and set the DMARC test\u0027s score (DMARCFailureScore) at or above the spam delete threshold, so that a message that fails a published quarantine or reject policy is refused, or quarantined, on arrival. Neither of the last two holds mail in the name of a domain whose DMARC policy is none."
        }
      ],
      "title": "Unintended Proxy or Intermediary (\u0027Confused Deputy\u0027) in hMailServer"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "ceab7361-8a18-47b1-92ba-4d7d25f6715a",
    "assignerShortName": "GitLab",
    "cveId": "CVE-2026-114478",
    "datePublished": "2026-10-21T15:12:35.847Z",
    "dateReserved": "2026-10-21T15:11:45.854Z",
    "dateUpdated": "2026-10-21T15:12:35.847Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}