HTML Injection in MailerUp double opt-in verification email

{
  "id": "a9003924a4440ef6f55c854ca8ab639228a828b3d6ebedb4fe82262da4ccdb44",
  "url": "https://osv.dev/vulnerability/CVE-2026-75872",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "HTML Injection in MailerUp double opt-in verification email",
    "summary": "HTML Injection in the public subscription form in maalfer MailerUp before 1.1.3 allows unauthenticated remote attackers to have the application send a message carrying arbitrary HTML, to an attacker-chosen address and from the form owner's configured sending identity, via the first_name field of the subscription request, which is interpolated unescaped into the double opt-in verification email.",
    "evidence": "osv:CVE-2026-75872",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-75872",
      "aliases": [
        "CVE-2026-75872"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/maalfer/mailerup",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "da4aedc9621911df4ce0cc8f0b321dd6d10f40a5"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.1.3"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "da4aedc9621911df4ce0cc8f0b321dd6d10f40a5"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "da4aedc9621911df4ce0cc8f0b321dd6d10f40a5"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v1.1.3"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.1.3"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.1.2",
            "v1.1.1",
            "v1.1.0",
            "v1.0.3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-75872.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.132436857Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/75xxx/CVE-2026-75872.json",
        "https://github.com/maalfer/mailerup/releases/tag/v1.1.3",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-75872",
        "https://github.com/maalfer/mailerup/commit/da4aedc9621911df4ce0cc8f0b321dd6d10f40a5",
        "https://github.com/maalfer/mailerup",
        "https://secur0.com/en/cna/cve-list/cve-2026-75872-html-injection-in-mailerup-double-optin-verification-email"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-80"
        ],
        "cna_assigner": "Secur0",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/75xxx/CVE-2026-75872.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-75872",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490689,
  "published_at": "2026-08-18T14:06:37.102+00:00"
}