Unintended Proxy or Intermediary ('Confused Deputy') in hMailServer

{
  "id": "3d437a44f207e0526a9a84f7c3bb6582e3ad28aaa43e1fb2727fa0db7a3e5c9c",
  "url": "https://osv.dev/vulnerability/CVE-2026-114478",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Unintended Proxy or Intermediary ('Confused Deputy') in hMailServer",
    "summary": "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's DMARC policy. When the server sent on a copy of mail that came from outside - an account's forward, a mail rule's forward, a Sieve redirect, a list's 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's From names, whatever the message's 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's own host name; and an envelope sender the message came with at a subdomain of a hosted domain was kept. Where that identity's SPF record authorises the server, other receivers' 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's mail to an outside address, and one of: SRS or the envelope rewrite enabled; a list whose bounce address is in the domain's organisation; an envelope sender at a subdomain whose SPF",
    "evidence": "osv:CVE-2026-114478",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-114478",
      "aliases": [
        "CVE-2026-114478"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://gitlab.com/hmailserver/hmailserver",
              "type": "GIT",
              "events": [
                {
                  "introduced": "e4b7163189ac6ce365bb954cf3e264e2e3105a18"
                },
                {
                  "last_affected": "e3c448aa66fc310b74d076884d54fae951296915"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "6.0.0"
                      },
                      {
                        "last_affected": "6.3.6"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "6.0.0"
                      },
                      {
                        "last_affected": "6.3.6"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v6.3.6",
            "v6.3.5",
            "v6.3.4",
            "v6.3.3",
            "v6.3.2",
            "build-inputs-1",
            "v6.3.1",
            "v6.3.0",
            "v6.2.28",
            "v6.2.27",
            "v6.2.26",
            "v6.2.25",
            "v6.2.24",
            "v6.2.23-alpha2",
            "v6.2.23-alpha1",
            "v6.2.22-pre6",
            "v6.2.22-pre5",
            "v6.2.22-pre4",
            "v6.2.22-pre3",
            "v6.2.22-pre2",
            "v6.2.22-pre1",
            "v6.2.21",
            "v6.2.20",
            "v6.2.19",
            "v6.2.18",
            "v6.2.17",
            "v6.2.16",
            "v6.2.15",
            "v6.2.14",
            "v6.2.13",
            "v6.2.12",
            "v6.2.11",
            "v6.2.10",
            "v6.2.9",
            "v6.2.8",
            "v6.2.7",
            "v6.2.6",
            "v6.2.5",
            "v6.2.4",
            "v6.2.3",
            "v6.2.2",
            "v6.2.1",
            "v6.2.0",
            "v6.1.0",
            "v6.0.0-B4",
            "v6.0.0-B3",
            "v6.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-114478.json"
          }
        }
      ],
      "modified": "2026-10-31T02:30:24.349407458Z",
      "provider": "osv",
      "references": [
        "https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.7",
        "https://gitlab.com/hmailserver/hmailserver/-/work_items/90",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/114xxx/CVE-2026-114478.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-114478",
        "https://gitlab.com/hmailserver/hmailserver"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-441"
        ],
        "cna_assigner": "GitLab",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/114xxx/CVE-2026-114478.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-114478",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 500152,
  "published_at": "2026-10-21T15:12:35.847+00:00"
}